How do conspiracy theorists get all of their coveted secret government information if it's meant to be hidden and the government would never hand it over?

One thing Alex Jones does is parrot things a caller said several episodes ago. He'll vaguely talk about sources, shuffle some paper around for dramatic effect and claim that nobody died at Sandy Hook.

Lots of other folks do a similar thing. They will say something innocuous that some of their audience will construe to be rightwing or part of a conspiracy and praise them for it. From there they get pulled more and more into whatever ideology as their audience pills them harder and harder.

Plenty of Q anon folks claim movies and TV have secret messages in them. There are a bunch of theories about why fiction is partially true. One is, all these stories are priming the population for social control. Cultiral programming of some sort.

Another is the Bible. The flat earth conspiracy theory is based on a particularly literal reading of the Bible. The writers of the Torah probably believed in a flat earth. This isn't surprising given their lack of sea faring history, most folks with large boats realize the earth isn't flat because the bottom of the boat disappears first. Plenty of flat earthers believe that society is trying to hide that fact so we don't realize we live in a divinely created snow globe. From there they concoct theories on how such a world could exist.