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.