Because some of us see our friends, family, and neighbors as more than a set of genes to pass on to the next generation.
And if those friends, family, and neighbors are clogging up a strained medical system that could even cause harm to us when we require such services for our own well being.
Because humans are more than their immune systems - I'd argue the Salk made society far stronger than a society requiring polio immunity as a precondition to live
Unfortunately all humans are born with weak immune systems, and sadly babies aren't fully vaccinated until they are ~2 years old. We protect them, because they eventually become our society. That pesky "future generations" concept.
You see, our immune system is built up over time with exposure to viruses, and inoculations. Then as we age, as our health decreases, our immune system gets worse again.
Personally, as I make my way through middle age, I hope that when I do reach my golden years I'm met with a little bit more compassion than "who cares about you, you're old and useless."
Funny enough, I know someone who has an auto immune system disorder, and recently found out this person is a lead figure in setting up Covid-19 response systems for major healthcare systems in the US.
And if those friends, family, and neighbors are clogging up a strained medical system that could even cause harm to us when we require such services for our own well being.