No, JT, "Anyone" wouldn't do the same thing you did. Some would, but most of the fine folks at this forum would not.
YOU offered an item at a price, someone agreed to YOUR price, and you backed off your offering price, which really was a "promise" to sell for that price, just as the prospective buyer "promised" to pay you the same price.
You broke a promise. I agree that it's ok to make a profit, but underlying that belief is it must be made ethically.