I don't think these are the same. If you get 15 marbles, arrange them into groups of 1,2,3,4,5 and give them the proper labels, you can trivially prove that the

I don't think these are the same. If you get 15 marbles, arrange them into groups of 1,2,3,4,5 and give them the proper labels, you can trivially prove that the sum of two groups of 2 equals 4 and not 5. The proofs for round earth are not as trivial. People have varying degrees of skepticism. Some are genuinely curious and are convinced by demonstrations while others are just contrarians. If you've ever heard Eddie Bravo talk, it's clear he doesn't care about understanding what shape the earth is and just likes to spout conspiracies.