I don't know about many. I don't know of any retail investors that do, and if I did I would have guessed that they'd be buying when prices drop, not selling.

Parent did say “sell / buy” (perhaps they ninja edited). A limit buy order is a basic tool of retail investors (like me :) ) and may have been what parent was thinking of. That said, I don’t agree with parent or great grandparent that the destructive impact is large.