Stop doing it? or Start diversified investment in Stock?
or Not at all?
Why would you stop when you will literally come back later to recover your money, I would rather to come back and just only invest that you can afford instead of all in because making something big is not a must in trading because that's not gonna make you rich instead the greediness will lead you to loss.
that means something is wrong if you continue to lose, do not force something that we do not have the knowledge about what we do.
but if you want to learn, never give up because later you will get the best results. if the long term better invests in parent altcoins the results will be very good.
What currently is wrong with him is that he lacks knowledge. What you have said is what he needs right now, if he wants to learn, he should never give up but first he should prioritize learning especially from the mistakes he have done to get the best result in the long run.