When I was a teenager I loved conspiracy theories. The FEMA one was big even back in the 90s. The idea was the government used FEMA to control the population. Stories of medical testing,drugs in the water a food they gave, even entire towns disappearing in FEMA camps.
Oh, yeah, back before YouTube or even the commercial internet, there were various crazy political groups that would send their videos to cable-access stations around the country. You would sometimes see their stuff played on late-night cable TV. I vaguely remember one that had to do with old rail yards being converted into FEMA detention camps or something. There was even an X-Files episode or two that riffed off of this stuff...it had quite an impact on '90s culture. The "FEMA camp" nonsense was even featured on Jesse Ventura's ridiculous TV show.
They think conservatives are going to be rounded up into FEMA camps. The earliest I remember hearing this is under Obama but it might have roots going back further.
I don't remember hearing specifically about FEMA camps before Obama, but of course it all builds off the various American iterations of the Protocols of the Elders of Zion - Jim Birch Society - New World Order - QAnon
I think it's conspiracy that started from conservative talk radio. Which makes me think it was initially something more banal like passing the blame on Katrina handling fuckups from Bush to the agency, and got Flanderized over time.
I'm taking a stab at the dark here, but I think chuds have this new thing rn where they're saying the current admin has politicized the hurricane that hit the USA. So FEMA is just a part of that.