That's risky, before engaging in trading cryptocurrency, it would be better if he would learn first about cryptocurrency and some basic knowledge about it before engaging in trading or investing because doing those things without any prior knowledge about it would be a bad ending. The worst case is he might blame you for every loss he will have in the future.
Thats why He is there as friend , to guide him all the wat , but OP feels bad if something went wrong when this is behind his hands, the interest comes from His friend so let him be.
the more he give advises is the more safer the friend can get.
One thing I must tell you op is that his passion and interest matters a lot because there are some people who don't have passion or interest but would want to venture in trading due to the profits. If you have fully explained everything to your friend then let him decides for himself whether to further continue the trading or not, so that when there is any lost then he would bear the consequences by himself. The best is to open up to him and roll along with him otherwise him might make silly mistake and still run back to you.
and what kind of interest is showing , means he is capable in what ever may come , actually that is the sign that the person in topic is strong and passionate and that is what crypto market needs nowadays.