I tried a few hours ago to make some money with the ranking system, by making low risk bet of ~4 usd. Just lost 8 to get 1 or 2 usd for ranking up.
So in the end it is quite hard to earn money in those races, somedays you win and some days you lose.
Yes, that happens in the game with provably fair system, in those games sometimes a player gets lucky and wins more amount than what they bet and sometimes they lose some money. However, the ones who're very lucky end up making 10x to 50x or even more with such bets. It's not easy to win money in those races but the ones who love the games often try again and again, and after some good tries they not only make money with their bets but also become part of that daily race and earn rewards there as well.