Operating a BTC gambling site can be extremly profitable thing, primedice's owner stunna, he makes at least 20K BTC per year. Many other big gambling sites like nitrogen, betcoin, fortunejack are making plenty of bitcoins everyday. But most casinos can't make huge money, operating casinos is not easy, it is similar to gambling and trading, always winners and losers, you need the best marketing team, it is the key of SUCCESS.