Over a bottle of wine, your friend bets you $10 that he can convert your $50 into $100. Now, you both might be too drunk, but will you accept the bet?
There is no logic reason behind accepting the bet. You know that your friend wont be able to convert the money and he will lose the bet. But he has only $10 to lose, while you will be giving him your $50. Thus, even if you win the bet, you lose $40.