I'm sure operating a bitcoin gambling site is very profitable but unless you're a very early adopter it's probably too late for you now unless you have a lot of money.
You're going to have to be able to afford to pay every users wins, if they win big can you pay them?
i don't think there are a high profit anymore, look at this place there is too much competition, and the big boy have already all the customers, you won't get much but the investment to run this sitr still is big, and risky, and aditionally you need trust at the beginning or no one will jump on your ship, and to do that you must lower fee and your edge, which mean lowering your income for the first months or two, not worth it for me