Who's behind the Conspiracy Theories- Illuminate, Trade Center, etc.? (Is it China, Iran, al-Qaida)?

I have seen so many people convinced of the major Conspiracy Theories- The New World Order, The Trade Center Demolition, The Faked Moon Landing, The Collapse of the Dollar and Marshal Law (soon), Planet X (Comet Elenin) and The End of the World in 2012. Who is behind this? It seems like too much bull to all be true at once unless we are in the twilight zone? Are these sociopathic mad men (and women) trying to convince us of these theories as a way to get some meaning out of their miserable lives? (And all the paranoids and miserable people who fall for them) Or, is there a more sinister plot like China, al-Qaida, or Iran trying to destroy America? Or, is there some big event about to happen?