Usually this is sort of promotion of exchanges, specially new one to attract crypto traders to their platform. They offered rewards for joining this competition, depends on the price.

Some are well experienced, perhaps they have it already from forex or stock and they carry it over to crypto. Yes there are differences, but they have a grasp, specially reading charts to that is a advantage here. There are full time traders, but I wouldn't say that they make profits all time. None are, there are no perfect traders not just here but in all markets as well. Nobody is perfect so no one is immune from losing. That's why we always tell to learn how to mitigate risk.