nobody can explain how your 'gravity' works--why objects of mass are supposed to attract. your bucket theory makes life on the 'outside' of the bucket impossible as the people would be thrown off. And since it's rotating we're all thrown off.
besides, maybe certain people in the aerospace industry have quite a lot to gain from claims that the earth is round. not only money, but in prevention of chaos. Also, if an Astronaut came back claiming that the world was flat, you wouldn't be the least surprised as the government locked him in a mental home never to be seen again.
I have a totally unproven theory, and I don't know how to test it:
The repeating pattern theory. Nature repeats itself in patterns... what if our universe was a giant, flat, infinitely repeating pattern. What if there are other you's a set distance away--typing on a computer just as you are now, all unaware of the others existance. "round earthers" have an infinite universe, so flat earthers can have one too.
When you fly around the world, you're departing from one copy of your life and arriving at the next. Since the other copy of you left this location as you left home, it would appear to your new family as if you'd just arrived home from a trip.
Perhaps the sun, moon and stars are also infinitely repeating patterns, equal in distance from their copies.