In my opinion, we should never take any kind of loans to do buy something we can't afford.
We have to plan out well and think of every possible risk before actually doing it.
What if your friend takes the loan but suddenly the market crashes and he loses half of the investment.
It will turn out to be a nightmare for him.
Instead he can take out the smaller profits, save it and then use it again in future as a bigger amount to get a bigger profit.