OP, if the Neg F'back was demonstrably unfair, I hope ebay removes it

Yes, it's easy for Buyer to leave Neg Feedback and there are some who will do so, as you say, simply because they can, in the same way some shine high-beams in other drivers' eyes or rip off the welfare system or falsely cry rape.  Some creatures are unevolved and a burden on the rest of us

I'm sorry it's happened to you and can guess at your frustration and anger.  It's in the hope of destroying someone else's peace of mind that the unevolved creatures do these things.  They'll very probably return to earth as cockroaches and flies

Not all us Buyers are like that though.  Most often I choose to leave no feedback at all when a buy's gone bad, although on one or two occasions I've left Neg Feedback to knock the complacency out of bad Sellers, for the sake of other Buyers

Hope you have the Neg removed and that the rest of your day is better  🙂