How much BTC do I need as a bankroll to start a dice site? (Excluding development)
There is no exact number of how many bitcoins you need to open a new dice site, maybe 50-100 bitcoins. It's depend though, if you have many players you need more big bankroll. For early start, maybe you only need 10-25 btc.
I agree that you need a lot of Bitcoin in order to have a great experience for people. Winning and losing would have an impact in your casino and as long as you continue with it, its going to be okay. I suggest to have a great GUI and solid program to have a meaningful game. No cheaters, beware of it.