so, when we are children in school, we are taught about the Earth being a sphere by the government funded schools. then when we grow up we are constantly reminded of this propoganda and we subliminally get manipulated into agreeing more and more with them. https://goodlogo.com/tags/globe
just some of the logos of companies we often see in our daily lives that are subliminally reinforcing the spherical image in our brains. its basic mind control and manipulation of the masses. of course most people are gonna think flat-earthers are crazy. because the idea of a spherical Earth is engrained so deep in your minds from the constant exposure to it.