I don't think this is entirely true. For example, Bitmex was more popular as a derivatives exchange before they introduced mandatory KYC. You would say when they introduced mandatory KYC for all their customers, they became compliant and fully regulated. Many traders abandoned for less strict exchanges.
So the problem is that soon there will be no exchanges without KYC and users will have to pass KYC on all exchanges. The same goes for the casino. Only very small exchanges and casinos with low liquidity or outright scammers will leave.