If 2 players want to play for money and they play against each other, there is nothing wrong with that. But I will never play Heroes for money online. In a club, it is quite possible that I will play.
P.S. Once, a strong player (one of the winners of the CIS tournament) persuaded me to play for 100 rubles, giving me a very large advantage. We started the game. Then he said that his wife felt ill and asked me to wait on my turn. I didn't see this message. As a result, he skipped 2 turns and started demanding to replay 2 turns. I said that we are playing for money, and I don't know anything about it. The player started talking to me about morality... :). Then, I agreed to replay 2 turns, but we didn't finish the game.