My husband was looking into mining crypto.
My take away from it;
The market is volatile (fluctuating more than a yo-yo dieters weight)
It uses a lot of energy to mine, if you’re going to mine it.
There are people who sell it and there are ATM’s where you can “cash out” your crypto.
Not sure any of this helps, but if you or your friend have specific questions, I can ask him if he has any answers.