Gambling percentage on the crypto economy has been on the raising side from a long time now. It is one of the most solid foundation to bitcoin, one of its main uses (of course it has many more main uses) but this is becoming fast one of the most appealing way to use bitcoin. It is super fast , no registration, no real life details. I think this business will continue to grow, in fact many FIAT casinos are really considering bitcoin to add as a form of payment (don't know if they will ask for KYC documents but its a good thing if they add it). It is a great percentage which I think will continue to grow corresponding to a growing user base who use bitcoin as a form of payment.
Very nice comment from you BitcoinSupremo, this is a nice review about bitcoin gambling generally and I doubt that anyone can add something more.
I also don't know, and for me it's foolish to even try to guess how much percentage of all crypto economy belong to gambling. What ever number that may be its in rising, bitcoin and other crypto currencies are used for gambling more each year and that us happening for the reasons you mentioned in your comment, fast, anonymous, do we need anything more?