How are you getting that idea? It didn’t bet much because it wasn’t at all confident, we don’t know what it would have done if it had been more confident.

Watson likes to play it safe, though, as can be seen in this demo game: http://www.youtube.com/watch?v=YgYSv2KSyWg&t=20m26s (I skipped ahead to Final Jeopardy.)

He was $16,000 ahead but one of the contestants could get within $1,600 by betting all of his money. So, naturally, Watson bet only $1,599 even though it was very confident (and ultimately got the answer right). That secured Watson’s win, no matter what the others did. (This is really not impressive or anything like that, if all you want to do is win the game, that’s what you do. Basic game theory.)