I would argue that real science tries to explain a phenomenon that's troubling. For example, General Relativity explains why Mercury's orbit couldn't accurately be described by Newtonian mechanics. But the flat Earthers start with no problem; they begin with a belief and then attempt to "prove" it by simple-minded "experiments" that, as you correctly state, are riddled with problems. And then they stop, having sufficiently convinced themselves of what they were already convinced of.

This is not science. It is infantile time-wasting.