"Why US Government want to organize this "Terrorist attack" ?"

I could go on for 1000 pages to explain this in detail but the short version is simple. It was done to fulfill the PNAC document titled "Rebuilding America's Defenses - Strategy, Forces and Resources For a New Century" which was published 1 year to the day prior to the 9/11 attacks (Sept 11 2000) and was authored by a wide range of people who would then move into positions of power via the Bush regime, a document that called for a "New Pearl Harbor" style attack in the United States which would be used to persuade the American public into going along with the wanted overarching PNAC agenda, which called for a massive increase in defense spending and the fighting of several major theater wars in order to re-establish American military dominance (which is exactly what took place in the aftermath of the attacks).

Amalgam Virgo, Vigilant Guardian, Global Guardian...
Gelatin, Urban Moving Systems, Moving Systems Incorporated...
Kroll, Halliburton, PNAC...
AMEC, Huntleigh USA, SPC International...
MITRE, PTECH, NIST...
NORAD, USSTRATCOM, FEMA...
Oh how deep the 9/11 rabbit hole goes...