much, much cheaper. and especially much much MUCH faster. And easier to organize
Charleroi - Budapest with airplane: 2 hours, one airplane ticket
Brussels - Budapest with train: 15 hours or 20 hours, depending on the route you take. At least two tickets, no way you can reserve them all in one go.
Brussels - Budapest by car: around 13 hours
(i'm not saying you don't act that way, but lots of people don't)