Hazink points out the obvious intention of these account buyers. They see the $10K as a fee to bypass a few years of building a positive reputation, so they must believe they can earn more than that. This can be confirmed if they asked philipma1957 to keep it quiet. The account owner decides if they can earn more than the offer and if not, the scummy ones may sell.
That's basically because these guys are not actually buying an account in the real sense they are aiming for reputation. The fact is every single account on this forum has its own level of reputation and they are looking to get one with a high level of reputation to be able to pull off something big which is obviously scam like you mentioned.
I think this is one of the reasons why some very reputable members have some tags on their profiles to probably stop scams like these from happening.