My favorite example of this is the tinfoil hat conspiracy of the early 2000’s. An open joke in the tech community that the government is always listening and knows what you do online.
Echelon[1] and Room 641A[2] (and others) were well known among niche circles a long time before Snowden. These "conspiracies" were the kind of thing that people would call you a crackpot for if you told normies though.
A reason others may refer to conspiracy theory supporters as "crackpots" could be attributed to the fact that there's now so many wild theories out there (UFOs, aliens, 9/11 inside job, etc). So if you support a few, then you'd be more likely to be considered a crackpot.
In other words, while those two examples were true, many are likely not.
Yes I do remember opening the news that day and my reality completely changing.
Up until then the “party van” parked outside your house taping your conversations was a joke perpetuated by schizos. Turns out they didn’t need a “party van” parked outside of your house.
then Snowden happened