For this particular contest, you have to sign up or confirm to the campaign manager that you are participating by sending your username, so there is no traditional leader's board. Yes I agree that you will need to be a high roller to stand a higher advantage but in the multiplier contests, even someone with small bankroll can get luck and hit over x1000.
If that's the case, it's fun, and anyone can win a reward. Contests about higher multipliers can be fun because your wagering or the amount used for bets doesn't matter, and all that matters is how big a multiplier you can hit. I don't remember very well, but I might have participated in a similar contest in the past, and because I usually wasn't lucky enough, I could barely get a good multiplier, and others were always ahead of me. That's the disadvantage of such contests; if you are unlucky, you will spend so much money on slots but don't get a good-looking multiplier to stand a chance.
Contests with leaderboards where users are ranked based on their wagers suck. You don't stand a chance of winning a prize in them because deep pockets won't let you near the top rankings. If you are trying to climb the ranks with a regular bankroll, just don't waste your time because someone will come, make a few bets with $20k, and boom, he's way ahead of you even though you've been grinding whole week or month.