I'm going to be the outlier by claiming the moon landing actually happened and the reason we haven't been back since is simply that there's no reason to go back. The moon is a dangerous place to visit, and the missions have little room for error. It is far easier (and cheaper) to send a lander or a satellite probe to find out what we are looking for. Landers have a multi-year timeline during which they can operate, while humans can only be present for a comparatively short period of time. We didn't have the technology for a good lander back in those days, nor did we have the extremely high-tech imaging satellites we now posess, so we sent people instead.
We brought back a large amount of lunar regolith, which is impossible to form under conditions on Earth. The only way for the quantity we obtained to have been harvested at that time was by hand, as the most advanced robotics in the world at the time could only recover less than a kilogram of material, far short of our 22 kilograms on Apollo 11. It has been extensively studied in hundreds of laboratories around the world and correlates to no known substance present on Earth. The technology it is often claimed was used to fake the landing didn't even exist back when the landing occured, as is demonstrated by this video:
http://gizmodo.com/5977205/why-the-moon ... tive-proof
We have images showing the landing sites from space, and no nation has ever contested that we visited the moon, be it friend or foe.
One day, we will go back, no doubt. But asteroids are the big issue right now, as they contain something the moon doesn't- resources that could be used for monetary gain. One asteroid can contain literally trillions of dollars worth of precious metals, while the moon has virtually zero known resources worth harvesting (until helium 3 fusion becomes a viable option). There's around 1,500 asteroids that require less energy to reach and return from than the moon, so it isn't like they're these impossible things to go out and grab. And then there's Mars- why spend billions sending some people back to the moon, when we could be the first to land on Mars and bring back Martian soil and regolith? If we're going to piss away money, we need to at least piss away money doing something
new. The only viable reason to go back to the moon is if we prove that we can travel beyond the moon safely, in which case establishing a base there would make a modicum of sense, rather than being a huge waste of money.
I'll tell you what's weird about people that believe in conspiracies- they never seem to believe in just one. It's either nothing is a conspiracy, or everything seems to be. Believe it or not, buying into this stuff doesn't make anyone crazy, and there's research about it, but you know, that's probably just another conspiracy:
http://www.nytimes.com/2013/05/26/magaz ... d=all&_r=0