By the way, we're hoping more participants will want to take advantage of the triple prize bonus - remember, you don't actually need to have, or risk, 1 BTC (or similar amounts of other coins); it's enough if you declare that as your starting bankroll. And of course, this bonus also applies to the consolation prize given to all participants who place the minimum number of bets, but end the competition without reaching the prizes - so, worst case scenario, you get a guaranteed 0.09 BTC free bet; best case scenario, you get over 3 BTC plus your ROI.

i am interested to change my bankroll to 1.000.000. dogecoin if true the condition like that but my worries is how the winner determined like you said in op below
---Determining the winner---
1. The winner will be the one with the better ROI % at the end of the competition
so if i made small bet with 1.000.000 doge bankroll registered its make worth nothing right? because the winner determined by ROI percentage. let's says if i won 100.000 doge profit in the end of this competition with bankroll 1.000.000 its gonna be 10% ROI . but if i register with 10.000 doge bankroll and make 100.000 profit its gonna be 1000% ROI. correct me if i am wrong. Thanks
You are wright, but please consider that in both cases you are
limited to a max bet of 5% of your bankroll, so it would take exactly the same effort to make 1000% ROI either with the big or the small bankroll.
So as I always try to explain, if you are confortable in betting 5% of the 1M Doge bankroll, whenever you think you should, because you feel it's a good bet, then there is no reason to stay with the small bank and not aim for the full prize.