If you have good bankroll then you can start gambling site.
That is right along with experience and skill of running a gambling site. It is also too much important to have good amount of money. Because there are always chances that one may make money from your gambling sites, which you have to play if you want people to continue trust on you and your gambling site.
You are guaranteed profit so long as you become the house because the house always have the edge but if you have no experience about setting this up then i will suggest you hire an expert to do it for you or you partner an expert because it involves money and with a little recklessness move you loose big time.