I am a FF. I want a good price on my travel, but I also want the airlines to make a reasonable profit, so their business is sustainable, and they keep flying me around.

Airlines overbook to try and fill up the A/C, not to screw you or me. They can't actually sell all the seats twice and keep the $$, they just get a change fee for you inconveniencing them with an unexpected change. I'm sure they'd rather 100% ticketed pasangers showed up.

If you buy a refundable seat (miles or $$) on an almost full plane, and it fills up, and you don't plan to ride, then you may have cost ME that seat I wanted and actually needed to get to grandma's. Plus you have guaranteed the airlines less revenue on that flight when you don't board.

Booking a bump run may be OK if you actually intend to sit in the plane. They sell you a ticket, you fly, or accept a bump. But to book a seat, check-in, and never intend to board is beneath my ethics. If lots of people did it, the airlines would have to raise rates, and overbook a higher % to stay in business.