The threshold for self experimentation is raising though. One can buy a plane ticket or launch a rocket with a camera to see that the earth is not flat. Telescopes that can see evidence of humans reaching the moon are more attainable.

My guess is that's why more widely believed theories are increasingly elaborate or are those that require more effort to disprove.

Religions too seem to be evolving to increasingly abstract beliefs or face ever more mental gymnastics to justify. (Part of the reason I'm no longer a believer.)