Honestly, both serve different uses. I will always love cryptogaming as the idea of making (any) money from video games seem like magic to me. I'm a child of the NES generation and the first time I heard about EverQuest real-money-trading it blew my mind.
Fishkeeping is so relaxing an, at the same time, you are protecting the lives of 20+ pets at once and death is just a part of the hobby. Plus, it's expensive!