Why do I like tournament poker better than cash games? It's just really hard with 40-50 BB to get away from a set regardless of the board. And if you have top-set second nuts, you are not going to escape from the unlikely change that someone called a 4x raise with 2d4d.
Still, no one to blame but yourself. Move in with top-set and lose... It happens, move on. At least it wasn't Kings into Aces pre-flop!