we usually see how the big whales wager huge amount of money and have high chance of getting big multipliers as risk reward return is directly linked and for these contest they will pour out more funds into the slots and top 70 positions will be filled by them only so the low rank and small gamblers don't have a big chance in these competition but if was something else then they might get a share in prize pool but still a good and big competition from duelbits side.
That's why I like the lottery system type of competitions. That way you get like 1 ticket for every 500 dollars you wager, and yeah they could wager 1 million dollars or whatever and they could have a bigger amount of tickets and they could win something more, but at the end of the day we would all have tickets and have a chance to win.
This is why it is a far superior method to make sure that everyone plays, but at that logic would whales gamble as much as they would gamble now? I do not think that they would want to. So, you could combine it, like if you have 15k to giveaway, make it 10k for the first place (or you know 5k 3k 2k for top three) and then the other 5k goes to lottery winners top 10 list type of thing.
That's exactly the reason why most places don't do it. If they do "let's see who will wager the most", they may get thousands of bitcoin worth of wagering, and maybe dozens of bitcoins lost.
All the above, if they do lottery style then we are going to end up with something more like hundreds of btc wagered, because whales could wager more than thousands of people like me, and when you do not have the support of those whales and they are not working hard to be at the top, the difference will be bigger than the people like me who would wager. That's why it's better to make a competition, that way they could end up with a much better result for the casino.