Those "scalpers" and "flippers" you complain about are helping to support the market that allows you to sell your knives at a profit whenever you feel like it. If you can't see that, there's not much more I can say.
Do you honestly think the prices of second hand knives would go down if the number of knives available dropped because a few people weren't flipping a bunch of knives after every show?
If you do, you're delusional. I'd love to see the logic to support this idea.
In fact, there's data to support the exact opposite. Look at what happens to knife prices after the big shows - they drop for a month or two, because the market is flooded with a bunch of knives from the flippers.
I just can't comprehend how you argue that more knives being sold, in gigantic "here are 60 different blades I picked up just to sell" threads is somehow driving prices UP. That's crazy talk.
