These contests end up with very impressive scores at the top of the list. Keep in mind that in an entire contest, millions of hands can be played. With thousands of players competing, it takes great luck to appear even in the top 100 scores.
Some have wondered how a player can average hundreds of points per hand. In this case, this is not an accurate way to look at a contest session. Nobody plays 100 hands and wins them all. The top scores almost always contain a very lucky winning deal worth thousands of points on its own, which is just the nature of the game. A dealt royal flush (there are always several of these in each contest) in triple play is worth 12,000 points in itself.
If you evaluate the best possible winning deal for a game, you can be pretty sure somewhere in the millions of hands played, someone is going to achieve that, or close to it. If you are curious about how the winners achieved such high scores, click on their scores in the leader board to see the exact cards from their winning hands.
Of course, the more deals you play, the more chances you have at hitting those lucky hands. Someone is going to come out on top, and it could just as easily be your next session.