What does craziness look like?
Well, we known what delusion looks like -- people that believe things in spite of contrary evidence.
We've also seen what looks like paranoia, and curious strains of seemingly institutionalized paranoia, behavior that affects how people interact with other people.
I also debated with a flat-earther on another forum. Hans was convinced that the earth was flat and no amount of evidence from space would convince him otherwise.
Enjoy