You do understand that everything would have been fine if we simply pretended this virus didn’t exist, right? A few extremely old people would have died slightly sooner. That’s it.
And that's not even addressing that the at-risk group isn't just the old.
https://pbs.twimg.com/media/ES5U9YUXkAA1e7H?format=jpg&name=...
You might get to the point where you need to make a choice between who you're going to accept in the hospital (younger people then get the fast lane over the elder due to potential higher amount of life years being saved). I believe its like that in Italy at this point.
If old people quarantine themselves the chances of them not getting this disease increase. I know a few elder (including loved ones) who I don't want to see passing away, so I have an interest in this.
On a different note, I also find it selfish and distasteful to feel careless about big groups of other people based on discriminatory elements such as age.