Hi.

I run BitsinoDice which is open source. https://github.com/Bitsino/BitsinoDice

Basically, no site starts out passive, but may become passive later. The flow of money is simple.

Visitors -> Registrations -> Deposits -> Profit ?

The problem is firstly getting traffic. Secondly a dice site runs a house edge typically of 1%, however this is an average over many bets, you could lose the entire capital of the site through a few lucky customers.

So even if you are able to get a constant flow of traffic you have to look out for security issues. A security issue could also wipe out your profit.

Good luck.