?
All you have to do is bet on black or red in roulette. It's not exactly 50/50 as it still there is zero as a separate color, but the odds don't change much. Roulette is available at most casinos, so just pick your favorite platform or the one that gives you the biggest welcome bonus.
My question is where I can do this for 50 BTC
You want to beg 50 btc? That is huge op.
It all depends on how you want it but I think you can divide the fund into 3 places or more so you can conviniently paly what you want to play without much restrictions. Well I don't think there could be any available platform where you could bet 50 btc in a single game. This is too daily for me mate and to the gambling platform.