Just read through this thread and, whilst I understand that the veterans of the market is trying to give sound advice, some are being a bit too forceful about it. There are some lessons you only gain by LOSING money. I've lost money with CFDs so I know first hand, and boy does it teach you lessons fast. You can read textbooks, sources, etc. but at the end of the day, if you're trading your hard-earned, you will learn just that much faster, because that negative experience STICKS with you (hence your "lesson"). You can read about that bad trade through textbooks, etc. 10 times and still not remember it, you can even do that bad trade on demo accounts and it still won't stick to you to the same degree as if you did the real thing. Those who have traded and failed with their actual hard-earned will know what I'm talking about.
So asking him to not trade because he'll lose money is a little counter-productive, especially since he said he's ready to lose that money. There's many ways to learn a lesson, if someone chooses to learn it faster by losing money then it's his choice. It's his hard-earned after all, he has the right to play with it however he wishes. Hey, you can read a thousand textbooks before trading and STILL lose money, maybe just slower but you can still lose money. So just let him be.