175k is very insignificant, moreso if you're a cheater now.
It was also his fault, many people have mispriced auctions and lost millions without remorse from others.
You may keep or give it back.
If you do keep it, he'll probably end up hating you, maybe stalk you for a while, and if he's a regular on the boards, make a bitch topic complaining.
Still, others are just going to laugh at his mistake if he does make a topic.
enjoy your earnings man cheating or not it was the person responsibility to indicate the correct price its not a perfect world so its up to you how bad u feel haha