I think it’s more nuanced than that. I can understand both sides perspectives, seller and buyer’s. Sometimes as a seller you post an item by mistake hugely undervalued. And then you get bombarded by emails and people trying to gain an advantage by offering more. It’s easy to fix your mistake by taking the best offer and citing the rules of capitalism as an excuse. I have been a victim of this. I bought a set of windshield gaskets only for the seller to refund my money because he later did some “research” and found out they were worth more than what we agreed to and I paid for. I felt it was a dick move but then again people are fallible and everybody makes mistakes and I have learned to forgive.