I don't think it's a good idea these days, there are a number of reputable bitcoin casinos here but they've been going for a number of years now, I think money has already been made there.
A lot of the newer casinos where you could potentially make good profit by investing in them are unproven trust wise, I just don't think it's worth the risk.
Yes, you can make a good profit if you invest on a new gambling site. But you should invest only if you know the admin and think that they will not scam otherwise high chance that they may cheat investors. So I suggest even though profit margins are less go with well-trusted sites for these investments instead with new sites.