The question seems to be: IF you want to go to the stadium to watch the game, would you sign a waiver. Not IF you would go to the stadium in the first place.
I don't see what the issue is that IF someone has the choice to sit in the stands and watch the game in person that they would be admitted only IF they signed a waiver that doesn't hold anyone but themselves responsible should they catch Covid. Signing a waiver doesn't affect whether you get Covid or not. It's only an issue of liability.
Does anyone not know that Covid can harm you under certain circumstances? Of course not. So if a person makes the choice to go anyway, so be it. This ought to have nothing to do with some "greater good" or how it affects other people or whatever. That standard could be applied to just about anything of any potential to cause harm. Frankly, the fiction of "the greater good" is the core message of Communism. And we've all seen how that plays out in reality, not in some idealistic theory conjured up in an ivory tower by some Sociology professor.