I can only suggest you test one by one of all casinos here to find the right casino you want because today, it is difficult to find a casino where you can bet 50 BTC. Besides that, playing with 50 BTC is too big and even if Stake allows you to gamble with 50 BTC, your profit is just 5 BTC, as @seoincorporation said and that is not worth doing. Using 50 BTC to gamble will make casinos suspicious as they rarely have gamblers who gamble with that such big BTC amounts. So it will make them ask you to verify your account and make sure you are not doing illegal things.