If you look at the value of the picks traded, I think the Lions gave up too much but these trade values never account for the player you are acquiring.
The largest crowd was 2018 so it's not like they are making bigger numbers each year. 275k would basically be 2.5x the Big House. If this crowd is snaking down Woodward and into Hart Plaza, it's not hard to fit 275k there.
Cousins is old and coming off serious injury. I don't think it's a bad idea to take a QB. This is basically want the Packers did with Rodgers and Love. Not sure Penix is the guy and at 8.