Money. It just comes down to the money. Playing these games is money in the pocket. If they don't play, that money is gone and it will never come back. A schedule isn't fungible, it's final.
I am sanguine with regards to these teams playing. Yes, people are at risk but it seems like the players overwhelmingly want to play. And, again, if you're a senior and this is it, and you will never play sports at this level again, I genuinely understand why they would want to play.
So I personally find the teeth gnashing to be a little much. Continually saying, "This just shouldn't be happening," is as extreme and ridiculous as people saying, "The stadiums should be packed to the gills with people."