I don't have much sympathy except in very specific instances.
1. Players who themselves have one of the pre-existing conditions, like diabetes.
2. Rookies/journeymen players with families who haven't had time to make life-changing money.
3. Those whose wife will be delivering a child during the season, and even then, I would try to ride as long as I could.
4. Those who do not believe their marriage could survive 4 months apart.
There might be a couple more reasons I could sneak in.
Otherwise, these guys have resources far, far beyond what the average American can dream of. They can sequester themselves while still providing luxurious levels of comfort for their family and compensate other people to provide the day-to-day tasks the players themselves usually handled, if any. They also have access to top-notch medical care and as frequent of testing as they desired.
I understand some of them could have significant others who have concerns, but we're talking about a maximum of 4 months. That's less than our military members regularly deploy from their families, and they can still arrange for distanced visits or quick testing prior to any visits.
In the meantime, they are providing a shot of much needed morale and distraction on a national scale, not to mention reducing the economic impact caused by further absence of their sport.