I agree with your assessment of cryptocurrencies. Here is a thought experiment that I use with other people: Ask yourself why none of the top 10 global investment banks have started their own crypto exchange. Now, add the 20 largest stock, futures, and options exchanges. Still none. After all, it is "just" market making (with a bit of clearing, custody & execution services). What is wrong with this picture? For me, the real issue is that KYC (know your customer) legal requirements will drain all the profit from the operation and expose the ibank/exchange to enormous legal risk.

Another one to make you scratch your head/chin: The world's busiest crypto exchange is Binance. The Wiki page literally says: "Headquarters: Unknown". How can anyone trust a company like that? Who regulates it? What enforcement agency will help in the event of fraud?