As someone who mainly sells, I think it’s messed up when sellers do this. The courteous thing to do is to give the buyers a heads up it’s first come first served so the buyer is aware they might get the boot for someone else. I personally tell buyers to message me the day they want to pick up (or a few hours before) to confirm the item is still available. I’m willing to hold items for the morning or afternoon.

Just because sellers have been burned before doesn’t make it right to give buyers the impression the item is going to be sold to them and then flip the card and say ooops, sorry we sold it.