Actually there's different between Crypto investment and trading, did you mean advising his friend not to go into trading? If yes" i think that's a good advice, because the risk that is involve in trading is very high to be compared with the risk in Crypto investment. secondly trading also requires more knowledge than Crypto investment, i think he did absolutely well by telling his friend about the bad experience he had in trading and also advising him not to go into trading because he wouldn't want his friend to Also have the bad experience he had.
He should have let his friend know the reason why he had a bad experience in trading, don't you think? A person who gets into the market and starts making trades without gaining enough knowledge will surely have to face the consequences. You can't become an engineer without education and learning about the field, so how can you expect to become a trader without learning about trading and everything necessary for it?
People often don't understand this, they get into the market without knowledge and start trading without making any research or even knowing anything about the cryptocurrencies they are trading and then they complain that trading is bad, I know it has its risks but that doesn't mean it's bad, everything can be bad if not handled in the right way.