Even if you do get your hands on that script, you have to deal with security updates, patches, software updates etc.
You also need to have a big starting bankroll and make sure that no one cheats on your site and robs you.
It's a hard task and there won't be a tutorial on it. It's literally like starting your own business.
Agreed, I have a bitcoin blackjack site and don't have anytime to promote it. I'm either going to look for a partner or sell it... just not enough hours in the day to do everything.
Get a partner!
@Dalyb: It's a lot harder to start from a script (despite it feeling easier), especially when you are not familiar with programming in general. Maintaining and modifying it will take time and debugging to do. This is true for a lot of things. It's better to know as much as you can about it from the get-go, and you can deal with these problems easier. Don't expect you can just sit around and watch your site become super awesome. Don't do it when your main goal is to be rich. It doesn't work that way.
It's not intuitive that it's more complicated to start with a script than program a new software but I understand why it's more complicated because you have to adapt to something you didn't build and look for flaws.