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?
Trading is not easy and it is a complicated challenge that requires many things to succeed.
You will need to have knowledge of the market in general, trading in either fundamental to technical things, understanding of the psychology of market cycles, capital and risk management strategies then choose a proper one that fits with your own characteristics, and very lastly you need discipline to apply knowledge into your trading practice, to get profit.
Many things can cause losses for a trader especially in this volatile market. That man can make many bad mistakes from lack of knowledge about trading, the market cycle, risk capital management and poor discipline too.
Generally I agree to advice newbies that it's better if they don't trade but focus on investment, long term and invest with pocket money.