Answer:
Borrowed money should never be invested because the outcome is never secure. While there is a possibility that the money in question may be increased, that isn't an ensured outcome. Also, if the money were to have a payoff, there wasn't a specific amount of interest set for returning the money. So, in theory, all of the money that was earned during the investment isn't your own. And that's not even mentioning the possibility of losing all of the money in question.