It could be profitable but I think you would need a good marketing(signature campaign) to accomplish this and this will cost a lot of money.
To start such a website you would need investors that trust you and you would also need good developers plus a good marketing, so I think it will be a hard task to do this.
Signature campaign is not the only way to advertise, there are many other ways to advertise and all requires not small amount of money/btc.
But I agree that it is not an easy task to start a gambling site, need a great plan, preparations, and of course money.
That's true for sure, establishing a gambling sites needs a careful study by the investor, he needs to know the market especially the bitcoin prices, he needs to study the competitors and copy those good strategies and improve the weakness he can see in some of the casinos, in that way you can be able to compete with other established casinos.