Actually at university we once sent a balloon up with a camera on it, and we could not see a curve. Have you send any cameras up to see this curve for yourself?
Quite tempted to say "yes" to see what your response would be but that would be dishonest.
The honest answer is no, but while I can't sensibly comment on your attempt
Good, that is the whole point! Don't take my word on it, don't take someone else's word on it, but go out and do your own empirical testing. If you keep your mind open I am sure you will find that the idea of a round earth is not as self-evident as you would think. Heck, you might even come here to argue for FET in due time.
I've seen plenty of football from amateur balloons and of course the multiple space agencies which only backs up what we've known about the shape of the earth for thousands of years.
I don't know what you mean with football from amateur balloons. Did these amateur balloons show the curvature of a football? I can believe that.