Nah! there aren't any gambling site now to provide such a huge win, the max one can win in one roll is around 110 btc.(on bitdice) correct me if i'm wrong.

There were some bigger winning than that,
BTC248 and
BTC250 in single bet!
Dude's back for more with a seemingly endless supply of BTC and the largest win the site has ever seen...

Some big bets earlier, here some of them including
BTC250 profit in 1 bet - which is probably a new record for BetKing

Brings his total profit to +257 on that account, congrats!
I guess this is proof that its very risky investing any type of bankroll on any up and coming gambling site. Same with people a large amount of deposit on any new gambling site. Any early adopter with 10000 BTC in their cold storage can easily come and clean out a gambling site completely. Look at Roger Ver or Loaded who got like 50,000-100,000 BTC to play around with back and forth.
I think you might be right about it, the early adopters may be a realistic danger for any gambling sites, if they really want to come up with their funds on gambling.
On the other hand, I would say that people having more than 50,000 BTC do not gamble, there are greater ways to spend this money for investing purposes, or just for increasing your life status.
Also, I have to say that having 50,000 or 100,000 btc has some disadvantage: try to cash them

IRS audit will show up instantly, or you will be charged guilty for laundering money.
Gambling is risky, you cannot expect that having 50,000 btc will make your bankroll rising for a constant time.
You always lose at the long term, remember that, big balance may not cover that up plus you should bear in mind that we also have max bet on every casino.
I am pretty sure if some people had 50,000 BTC and they withdrew it for cash they wouldn't mind about paying the taxes. Withdrawing $100,000,000 dollars and after tax getting able to keep $60,000,000 is still alot of money. Most people wouldn't be able to spend that much money even in their life-time.
Point is that its very easy for someone to entirely empty out a sites bankroll with such huge max BTC amounts being possible.