Off course, they chassing the prize.

Usually, there has some reason why user finally decide to participated Reward + How fast or lot waggering is being made by other user + total user participated in the tournament. These are 3 reason, people starting to participated in the tournament.

Some user is also taking tournament as acting for cashback. Let's said he making some big waggering, and lose the deposit these prize can came as cashback lose + don't forget daily rakeback, weekly and monthly. At least you can get 50%+ recovery your loses with these (like just acting as cashback loses)