I would highly advise against leveraged/derivative trading but that's from my own perspective as I have been burnt many times before. And I am quite a veteran trader, so think it over.
I don't know if he loses certain trades as i have seen only wins when i skimmed through his profile sometime back but i think he's obviously aware of the dangers to trading using leverage so you are wasting time advising him against it.
Some questions I have for OP are;
1. Do you ever make bad trades (ones that hit your stop losses)
2. If yes, what is your win rate like?
3. What is your risk/reward ratio or you don't consider RR?
Yeah everyone does, was lucky today I think I made like 9-11 trades and hit a painful SL on one.