People crazy. Why flat Earth? You can fly by plane and see everything.
It's an experiment to show how unbelievable stupid people can actually be.
Q: As a passenger on an aircraft, how is it I can see the curvature of the earth?
"Quite simply you cannot. It is widely stated you would need to be at a height of at least 40,000 ft to get even a hint of curvature if earth were round. Commercial aircraft are not allowed to fly this high. They are only allowed to fly just under this altitude. 36,000ft might be typical. In addition, the windows on commercial aircraft are small and heavily curved. Even if they flew high enough for a person to see curvature, it would still not be visible to passengers."
https://wiki.tfes.org/Frequently_Asked_QuestionsThis is the general Flat Earth response. Seems reasonable.