When I mention Flat Earth, my friend & family think I’m crazy? Yes, it is a normal reaction. It’s best to not bring up the subject again. You have, however planted a seed of curiosity, and most smart people will actually research the subject. You must understand, that WE have been indoctrinated since childhood, to believe the World is a Sphere.
So, on a Flat Earth, there would be no Curvature? We cannot observe the Curvature. We think we do, because someone told us so. Many have researched and tested the said observable Curvature, but failed to prove it.
If there is no Curvature, then we should be able to see Mt Everest from America, right? No, for one visibility and our limited vision, cannot allow us to. Even with the most powerful telescopes made, visibility will get in the way.
If visibility prevents us from seeing far away, how come we can see stars, planets, galaxies, constellations? For one, when looking up, the impeding air pollution, clouds, water vapor, smog, etc., that hamper visibility are no longer in the way. (And then, what if all those celestial objects where not as far as we are told?)
What about the international space program? NASA is lying to us. Lets check out the Space page.
What about Satellites, and the Space Station? Only NASA and the other space agencies know the truth. Satellites could very well be hanging from balloons.
What is the real shape of the Globe? Perfect Sphere? Oblate spheroid? or Pear shaped as Neil de Grasse Tyson says?
Why such a difference in Plant and animal life between Arctic and Antarctic? Antarctic, the dead zone? Not much sunlight in that zone, at least not long enough.