I have met a few who think the earth is flat. There is a flat earth society. I simple ask them why the earth is flat but the moon and sun is round. The reply was I was stupid.
Theoretically, they are correct. If you drive 1000 miles west, there is no curve. The Earth is flat for us. You have to get really high up to see the curvature and nobody has time for that.
I’ve read that true flat earthers believe the Flat Earth Society is an illuminati org designed to make them all appear foolish.