I think cryptocurrencies are an obvious trash fire. I also think they contain all the elements (flow information asymmetry, bad price transparency and consistency, high technical volatility, and zero capacity for fundamental edge) that make it quite profitable to make markets in, i.e to be the house in respect of. Combine that with the general culture around cryptocurrencies, which I suspect is averse to litigation, and you have a supremely profitable business.

One need not love what they trade. (I do see an ethical issue with selling retail customers such products.)