Trading securities involves risk. I bought GE stock that dropped 50%. I understand the game. I'm not broke from that. But when investing, you're never supposed to put all your eggs in one basket. Cuz you will take some L's. He should not be investing if he doesn't know how it works. Educate yourself on something first before risking your money on it.
As for crypto currency, i'd never invest in it because I don't know what that security is backed by. When u buy a stock, you receive company equity in return. When you buy a bond, you're basically giving a company or municipality a loan that is repaid with interest which is the reward for investing. He gotta smarten up. When u buy Bitcoin, u get fictitious money that I don't understand.