If they are strictly doing business in crypto and fiat isn't part of the deal, then these sites shouldn't be subject to KYC laws. On the other hand, we don't know how the rules will change in the coming years. I seriously wouldn't be surprised to find out at some point in the future that even sites strictly doing business in crypto will be forced to go through all these laws. The environment within this market isn't even for 5% regulated, so things will take time to shape and become clear what the deal actually is about. It could also be that a limit system will be put in place. Everything below 0.10 BTC for example will be free of these laws, where everything above that requires verification. Not gambling is an effective way of not being subject to these laws right now and in the future.