What is the motive in the theory that 9-11 was an inside job?

The best answer chosen by the voters to this question on Yahoo Answers states:

People say 9/11 was planned to get us into a war so military suppliers could make money. This idea is incorrect because we don't need an attack to get us into a war. For example, the direct result of 9-11 was the attack on Afghanistan, a relatively small operation.

On the other hand, look at the big operation, the attack on Iraq. We didn't need 9/11 for that. Iraq was simply justified by Bush saying Iraq had weapons of mass destruction. He explicitly stated it was not due to 9/11 or terrorism.

Wrong; the George Washington blog explains:

Why are we in Iraq? WMDs, you say!

Actually, President Bush's March 18, 2003 letter to Congress authorizing the use of force against Iraq, includes the following paragraph.

(2) acting pursuant to the Constitution and Public Law 107-243 is consistent with the United States and other countries continuing to take the necessary actions against international terrorists and terrorist organizations, including those nations, organizations, or persons who planned, authorized, committed, or aided the terrorist attacks that occurred on September 11, 2001.

White House's false linkage of Iraq and 9/11 which allowed the Bush administration to claim that Congress had voted for the Iraq war. So looking at who was actually behind 9/11 (not Saddam Hussein) is important in connection with the Iraq war.

The answer then goes on to state that:

People say that insiders bought securities that would generate profit after the 9/11 attacks.
Unusual stock and option transactions have already been investigated and were found to be ordinary transactions resulting from well-known business expectations. This was done by the 9-11 Commission & others.

Furthermore, financial transactions are completely transparent: We know exactly who did them. Only a fool would simply buy 10s of millions of put options (anything less would not be worth it) and then go blow up the WTC--we would know immediately who did it.

Moreover, insider-trading is a crime and the Security and Exchange Commission (SEC) routinely monitors all trades for excess profits. There’s no way to cover it up.

Also, many of the people who died in WTC 1 & 2 are in the financial industry and many of their close friends would be in finance also. Surely, these friends & colleagues of the deceased would all have complete access to trading data. They would go crazy with anger if they could find anything fishy in the deaths of their friends. But, the thousands of people who work on wall street are quiet indicating no unusual activity.

If these transactions are real, then (1) who is the biggest profit-maker, (2) how much did they make & when, and (4) how does this activity compare to historical transaction volume that ordinarily occurs? It's specifics that make a claim plausible and verifiable. It's vagueness that suggests it's all made-up.

Until there is an intelligent answer for the above, we can safely be assured that all these "millions of transactions" are a myth.

I'm actually going to accept this part of the answer, and get this, agree with the Screw Loose Change blog.

[UPDATE October 2014:

Economics Professor Paul Zarembka, has written in the past that the work of Mike Williams at the debunking site 911myths.com had caused him "to reconsider [his] prior conclusion of high probability of insider trading in put options" for American and United airlines stocks. I have previously stated that I believe the insider trading issue had been effectively debunked.

In this recent interview Zarembka cites new evidence that brings him and myself back to his original conclusion.]

This was what the person who answered the question considered the "two main motives that are given to 'prove' 9-11 was an inside job." Motives by themselves don't prove anything. The forensic evidence, NORAD stand-down, and whistleblowers, prove the case. They also forgot a few other main motives that flesh themselves out when looking at how the world would be different without 9/11.

From Steve Watson of the website PrisonPlanet.com :

Without 9/11 there would be no "war on terror".

Without 9/11 there would be no "clash of civilizations"

Without 9/11 there would be no war in Afghanistan.

Without 9/11 there would be no war in Iraq.

Without 9/11 there would be no war in… (insert any country classified as part of the "axis of evil" or defined as being 'with the terrorists')

Without 9/11 thousands of U.S. troops would not have been sent to their deaths.

Without 9/11 hundreds of thousands of citizens of Iraq and Afghanistan would not have been sentenced to their deaths.

Without 9/11 there would be no inaction on the Israeli-Palestinian peace process.

Without 9/11 there would be no civilian contractors in Iraq and the scandal that has followed them would have been averted.

Without 9/11 there would be no false military reporting (Pat Tillman, Jessica Lynch), and no crack down on the freedom of the press (banning photographing the returning coffins).

Without 9/11 there would be no Patriot Act.

Without 9/11 there would be no NSA warrantless wiretapping program.

Without 9/11 there would be no Camp Delta and no Camp X-ray at Guantanamo Bay.

Without 9/11 there would be no Military Commissions Act and no coordinated program of extraordinary rendition, indefinite detention and torture of those defined as “enemy combatants”.

Without 9/11 there would be no vast increase in secrecy and complete militarization of intelligence under the newly created office of the Director of National Intelligence.

Without 9/11 there would not be thousands of dead and dying emergency workers who are suffering crippling and fatal respiratory illnesses.

Without 9/11 there would be no vast increase in military and security spending that goes arm in arm with huge cutbacks in other key social programs (such as levees in New Orleans).

Without 9/11 there would have been no total abandonment of fiscal restraint, which has contributed to plunging the nation into an abyss of debt and looks likely to tip the world into a deep recession if not a complete depression.

And on and on and on.

Perhaps most importantly, without 9/11 there would be no "post 9/11 society/mentality".

The Motive for the 9/11 Attack
http://www.911review.com/motive/index.html

The official legend of the 9/11/01 attack is rather sparse on motive. Muslim extremists attacked the United States "because they hate our freedoms". This was the only motive articulated by the Bush Administration, but more rational motives were available to consumers of print media: perhaps Osama wanted to punish the United States for stationing troops in Saudi Arabia, and perhaps he wanted to provoke the United States into attacking Arab nations in order to recruit jihadists. But the issue of bin Laden's motive was never a big issue, since he had already been tried and convicted on TV on the day of the attack. All that was important is that he hated us, that lots of Arabs hated us, and that military action was required to stamp out the terrorist training camps in Afghanistan.

Beneficiaries of the Attack

The purely ideological motive ascribed to the elusive Osama bin Laden contrasts with the very tangible and material benefits that flowed to individuals and organizations within the power structures of the United States. Indeed, the number of beneficiaries is so large that attempting to identify them may shed little light on how the crime was perpetrated. Determining who had the means to execute the attack is more likely to lead to the individuals who planned and executed the attack.

Despite the near certainty that the vast majority of beneficiaries had no operational role in the attack, it is clear that many worked to facilitate it, aided its coverup, and actively exploited the reaction to it. Since many of these actions involved commission of crimes, their investigation and prosecution could be instrumental in unraveling the vast crime of 9/11.

Beneficiaries of the attack included the highest officials in the New York City and Federal governments, and corporations benefiting from policies enacted by those officials.

• George W. Bush enjoyed an immediate surge in popularity and the burying of investigative reports on electoral fraud by his brother Jeb's Republican election machine in Florida. "United We Stand" slogans propagated across the nation as Bush boasted of "smoking out" the terrorists.
• Rudolph Giuliani became an instant hero by immediately appearing for photo ops as the hands-on mayor at Ground Zero, and by taking command of the situation. He was exalted as Man of the Year by Time magazine while he managed the largest evidence destruction operation in history.
• The new War on Terror would become the umbrella for whole new levels of pork, unaccountability, and corruption in the nexus of government and industry that would fight the war.
• The weapons industries prepared for a new orgy of corporate welfare, as the Pentagon budget would be further bloated. Certainly we would need billion-dollar stealth bombers to smoke the elusive Osama bin Laden out of his cave.
• Vice President Cheney's company, Halliburton, would soon be getting fat no-bid contracts to rebuild the infrastructure that American bombs would destroy in Afghanistan and Iraq.
• The owner of the World Trade Center complex would receive a $3.6 billion payout for the destruction of the seven buildings, and would seek a second payout on the basis that the attack was two "occurrences" (because there were two plane crashes). Silverstein Properties had just acquired a 99-year lease on the World Trade Center, and a new insurance policy, in July of 2001. Silverstein would be ridded of those white elephants, the Twin Towers, with their obsolete office space and asbestos abatement problems.
• The Project for a New American Century got the new Pearl Harbor that it said would be needed to rapidly achieve its goals.

Related:

SEC Found No Sign 9/11 Conspirators Traded on Plot