Optick

Conspiracy has a negative connotation. Thanks to the CIA, when you start talking about legitimate conspiracies, you become associated with tinfoil hatters and schizophrenics.

WhyNoDonuts

I think that they intended to lump JFK in with us when pushing the term in the 60s, but he rose above it and it wasn't much of a thing until the 90s, when the x-files breathed new life into it with aliens ands such. Post 9-11, it became a label for truthers. (as evidenced to me by a financial trader and former delta-kappa-epsilon dude when he said "you're not one of those 9/11 conspiracy guys aree you?" -my reply was to let him know that I knew he was part of the Bush fraternity, and he shut right up)

It is engrained as part of a social response. If you aree part of the financial machine, you use "conspiracy theorist" as a derogatory term. I use it to show that I'm not an idiot.