Checkmate

Because there's government agents patrolling the edges, obviously.

Its such a long trip though maybe they haven't made it there yet.

So many people have tried, but never returned. They fell off.

Because the closer you get to the edge to more centripetal force there is flinging you off into space! Duh
The water stays because of surface tension.
This is science people.

Flat Earthers are just people from the Flat Universe who fell over the edge.

International law prohibits people from going to Antartica (the supposed edge) without going through lots of red tape.