Many stadiums are not a closed circle, but have separate upper decks with major gaps. Some stadiums I can name have clear street-level views of upper decks through these breaks. Line of fire, no need for long-range plunging fire. I only wrote this indirect plunging fire scenario because an average knucklehead can’t easily get the math, ballistics and trajectory just right on a first try. But there are MANY other ways an average knucklehead can do it, but I’m not putting them into the body of my main text to be a guide book.
A fair point for sure, and frankly, if I were intending to cause major panic/mayhem/murder in this way, there’s a much softer AND bigger target I just realized: college football stadiums. 90,000+ every weekend in many accessible venues.