Would be interesting to see most bets won/most bets won in a row with higher minimum odds (perhaps @1.7) so that it's not just spamming low odd bets. Or perhaps a challenge for most Live betting wins/highest Live betting ROI.
Could also go with more strategic ones, such as "Highest average odds on winning bets" though that might discourage normal betting.
User who wins the most with two consecutive bets (combined).
Meaning that if a user A loses 0.5 mBTC and right after that wins 3 mBTC, the result is calculated as follows:
-0.5 mBTC + 3 mBTC = 2.5 mBTC
Of course if there's a pair of consecutive bets with higher result during the same day, that pair should be considered.
In short, user with the best pair wins.
Biased towards $500 bankroll players. You're excluding all $50 and $250 players pretty much as well as those who don't stake the full 5% per bet. Those who are at a higher profit also have an advantage due to being able to place higher stakes. I like the idea, but needs some tweaking.