Gamling and speculation are certainly use cases. They're not the only use cases. Money laundering, drug sales, protecting assets against seizure, political diss

Gamling and speculation are certainly use cases. They're not the only use cases. Money laundering, drug sales, protecting assets against seizure, political dissent... basically anything where the Government / financial system has shut you out from the market. I say "useful" only in the sense that it clearly has uses. Even if you don't believe these activities are beneficial to society, you can still concede that they are useful in that people are using them.