Yes, you can to make dice website with 30btc bankroll if you limit higher bets, for example make max bet like 1btc but I think your profit won't be higher with limited bets because your website's customer will be small players and big players never play there. Also if you are going to make provably fair dice, thank I think you need better bankroll and if you can't that, than make an investment place in your website like many other dice website has but if there will bi investors, than some percent of profit will be your and some of them will be for investors.