How would anyone know who "bought it" unless they have access to Delta's revenue management system?
(Of course there was that passenger on one of my flights who "polled" the First Class cabin to see why the DYKWIA hadn't been upgraded because he somehow "KNEW" he should have been... The FA made him stop but not before I told him "because I was number one on the upgrade list and no I don't work for the airline or even know anyone who does" and the woman next to me told him "I am old, I am well off and I bought this seat"

)