You are correct, the best way to make a small fortune in baseball is to start with a large fortune.
But for every Mark Cuban there is a Jerry.
Why buy a MLB franchise? To make money, break even, or as a hobby that will cost you some $$? Perhaps out a sense of history and keeping a team in it's traditional city. Perhaps to join an elite club? If it is out of some history or wanting to be a part of MLB, then moving the team to the A.L. East would seem perfectly natural.
Short of the dig at 4E, that's a HoF post