not more than 30% maybe because the biggest percentage maybe held by miners and traders as we can see there are a lot of markets than gambling site. the volume too
Yes I think I second your speculative guess. Not many are using their bitcoins in gambling and so they are kept and sold at the right time the owner deems fit. It'll be really great if we have this percentage of Bitcoin owners into Bitcoin gambling as well.
Gambling industry in crypto is getting bigger, in fact it's one of the reasons why the crypto economy has progress this much. It maybe small in the entire industry but this is a big threat to fiat gambling and there is a big possibility that in the future crypto will dominate the gambling world and we investors will benefit on that.