I don't get sellers on COMC

[mooch]

I sent in 25 or so psa graded cards in the last month. These are all popular registry vintage cards that trade frequently. I priced them within 0-10 percent (under) of the low-end recent eBay sales when I auto accept a 20% discount, figuring they would sell relatively quickly. Half of them sold within 1 hour to major vintage comc flippers and were immediately reposted for 200% to 300% of what I sold them for. I have no problem with that--I got a reasonable price without eBay/Pwcc fees. Here's the thing I don't get: even with heavy discounts, these cards can be had for much less on eBay bin. What's the angle? I think this creates the museum effect, which I didn't find with comc 1-2 years ago.