It must be working for him - he's been doing this for ten years.
As such, how can you blame him? When I started collecting again after a 5-year hiatus, I was surprised to see some of these guys still in business (there are plenty of them) - sellers who according to my own sensibility about selling, should never have survived.
I suspect that they are selling a lot at much lower prices, via off-ebay offers, saving ebay expenses. Further evidence is that most of them have BIN's, but no 'Make offer' button.
There are at least two of these guys who I used to buy from regularly. I shied away from them for a long time, then simply made them reasonable offers and was stunned when I was never rejected.