Right ok, one thing flat earthers need to do for one minute is see the word as if it was curved regardless of your beliefs for a second answer me this question.
The Earth is huge and has a curve in it, the longer the diameter, the more the circumference and the more circumference the more distance you have to go before you change angle by one degree. Since all circles add up to 360 degrees.
So going by this logic, a ball with a diameter of 12,742km will have a circumference of 40,000km that is huge, now with the size of this, there is literally no way to believe that anything on the surface could possibly see any remote bit of curvature.
Make sense?
To further this, the Earth's surface curves one degree every 111km if looking through a cross section, are you lot trying to tell me that on an artificial horizon the width of about 5cm you would be able to notice a difference in angle of 0.000000045 degrees, yeah unlikely mate.
(if anyone who actually understands maths and has seen an error in my calculations or wants me to explain part of it, just quote it and I'll see what can be sorted, and if you don't have a bloody clue about maths, this note doesn't mean I necessary have made a mistake that makes FE viable)