Suppose you lent 10,000 to a friend and the friend promised to return it within a year. A year later, your friend doesn't pay you back and makes a bunch of excuses. Instead, he takes the 5,000 he has left to the casino, gambles it on the roulette wheel and by luck manages to turn that into 30,000 and pays you back 1.5 years later. I don't think you would be happy with that situation...