Sure, some people are stupid and can't handle simple math, but there is an easy explanation for a lot of those sell orders at quicksell value. The app. If you've been playing all year you could have thousands of duplicates in your binder. Selling them off via the game can be a slow and tedious process. I sold plenty of bronze cards at 25 stubs because I didn't want to waste my time trying to find them all in game, and I would just go through dupes on my phone while watching TV. Even the 100 stubs loss from something like a diamond bat can be written off in your mind as a convenience fee.
I ended up with almost every card in the game and 5 million stubs with nothing to spend them on, so the loss in sales tax didn't exactly send me to the poor house.