Flat Earth nutters can't even pass the first question in Dumbass Conspiracies 101 - Why would people in power even want to make you think the Earth was flat? What benefit is there to that?
Because they don't want us to know about whatever is on the other side of that ice wall, obviously. It's probably where they keep their gold or something. They have us believing that if you crossed Antarctica it would just be an inconvenient way of getting to the other side of the world so that none of us will ever try it.