Sorry, can you give me one good example of how someone can scam someone else using onemarket, taking into consideration that nobody likes to deliberately lose money?
Extortion. Scammer will pretend to the other party that he can afford losing the escrow and don't mind it, but if the other party sends him some amount of coins (less than the escrow amount obv) he will let the contract go through.
And then the person being scammed will send him even more money, even though he knows that the other person is anonymous and can keep playing this game forever?
Not gonna happen, makes no sense at all. As long as you're not stupid you would never fall for this. It's like saying email is unsafe because some people get tricked by Nigerian scammers.