This, despite Hoover's lifestyle (not that there's anything wrong with it, but there was then). Why do so many people scoff at the notion that the intelligence agencies of the US could be up to no good? I mean, it isn't disputed that Hoover was an SOB, a scoundrel who used his office's resources to extort basically anyone he could. That's conspiracy fact. And it went on for years.
Hoover was also incredibly effective, at least earlier on...so he had a lot of political support within the government and within congress. The president is only one chamber of power, people tend to forget that. Its nice to fixate on Obama, but the whole government is in on this...congress, judges, state government, local government, and even...I dare say...much of the citizenry.
Far-fetched? No President could unseat Hoover. Why would any intelligence and surveillance apparatus be any less self-preserving?