My interest wanes as the tournament continues

In the first place, there are just fewer teams to keep up with, and so the play does not require as much attention. But further than that, since I usually root for underdogs (smaller teams), there generally are fewer of them in the tournament at that point, and so there is just less to interest me. By the time we get to the Final Four, as often as not all the teams there I either positively dislike, or I just have no interest in them.