The biggest problem with conspiracy theories is the cover-up. I don't deny that governments are capable of lying and doing terrible things (cf. early CIA). But

The biggest problem with conspiracy theories is the cover-up. I don't deny that governments are capable of lying and doing terrible things (cf. early CIA). But I can't accept the idea that a massive conspiracy would stay secret. Any of the hundreds of conspirators involved would be an instant millionaire celebrity for breaking the news.