This is all about quantity and in the future there will be a massive adoption of the future and that makes it even more awesome for the bitcoins and gambling sites.
You are only partially right about quantity. Because from what I know it is extremaly easy to create and operate bitcoin gambling site (at least compared to standard FIAT based gambling services)
That is the reason we have so many cryptocurrency casinos around. But in the end people will pick their top services and there will be only few really good casinos left.
It seems easy but there is also a lot of cases whereby even bitcoin top platform exchange also got hacked and are in serious trouble.
In most cases hackers just capitalize on lack of imagination and human error of operators.
Most of these attacks could have been reverted if owners weren't so stingy about providing additional money for security, backup, cold wallets.
And some of these 'attacks' were even fake - and covered exit scams of untrustworthy businesses.
Usually not some but all of the attacks so far have been proven fake and are only exit scams maybe not of the businesses themselves but of an individual who worked or was working for them. Its good so far no large casino have not made any of this excuses to get players fund, but if it does so, then the profit would be smaller than of that of a lot of gamblers playing there, thats why so far we have not seen anything like this happen to approved large casinos in bitcoin.