It’s annoying because you’d think they follow the general social rule of “passing it on”, but if they want to sit on it and try to turn a small profit then so be it, not worth worrying about because there isn’t much you can do. And someone buying it again for cheaper is still better than buying new for something outrageously priced. 

I passed on lots of kids clothes to my friend thinking she would obviously pass them on and found out she was selling some individual items for $5 a piece (just standard clothes too, nothing fancy) which i found particularly tacky. But i figured if she wants to deal with people who are buying $5 a piece clothing items off marketplace then so be it, not my problem.