One of the forced bets (the whole amount of the minimum bet or the double of the small blind). Big Blind - also a person who sits to the left from the Button.
In poker, the only thing that separates any player from entering any tournament is the buy in. The worst player in the world can get into the world's most prestigous competitions, while the best player in the world not always can. All because of the money.
Winning heads up is great and all, but there's always that chance you could have been wrong, and you've been shooting with the second best hand. Sometimes, it's better and safer to just chase everyone else off the pot with some nasty aggression.