Yes, the free UBT games definitely are full of wildcat bettors, and aren't a good representation of real tournament play. It's frustrating sometimes, but hey, it is free, so it's all good.
The strategy I've had most success with is to bet the minimum for the first couple of hands, and hopefully a few players will go out. Often, the players that remain are small bettors, so then you can switch gears and bet big. If you get a big lead, sit on it until someone catches you. If it doesn't work, go sign up again!