before kickoff you would have seen hundreds of tickets still for sale...
and this doesn't even include the unsold tickets BYU had on Seatgeek and Stubhub.
And there is a zero chance this game sells all of the tickets. (note: BYU will probably still call this game a sell out - because that's what they do - but set you alarm clock for kickoff - log in to byutickets and you'll still see hundreds of unsold tickets)