I've read on this forum, in terms, that the space-flight and moon-landings conspiracies are financially motivated, viz, NASA tell the US government they need funding for such activities and then spend it one something else.
Books etc which I have read (or at least looked at the pictures) which show the earth as a globe date back a fair amount of time. If this is in fact incorrect and the earth is a disc, then the lie of a round earth has been perpetuated from a time before space travel was likely considered as a possibility. Before NASA existed and could soak up funds, what was the point of pretending the earth was round? While I agree that power generally is a motive, I'm less inclined to believe that knowing the truth about the shape of the earth would keep conspirators interested for a prolonged period of time.
Maybe this has been talked about already. If so I'd be grateful for a link to the discussion.