It certainly could be a conspiracy, but to believe it relies on ignoring very good evidence in favour of some rather dodgy stuff.
I know that, in general, anything I haven't personally seen for myself could have been faked (and even some of the stuff I have seen), but we have to make our decisions on the evidence available.
People think the holocaust was faked, that shape-shifting lizards run the planet, that JFK was shot by the CIA, KGB and the mafia, that the moon landings were faked. Some people might believe all four, but there are many who believe one theory but find another idiotic or offensive.
Personally, I think it would be easier to actually carry out the moon landings than it would be to fake them and keep up the lie for five decades.