It is to an extent about young and old, though. If you're young and healthy then chances are you won't suffer serious effects... but that's not really the point. If you're young and healthy and coughing Covid onto everyone, chances are you'll infect someone who is more vulnerable.

For the young and healthy, vaccination isn't so much about protecting the individual as it is about protecting the more vulnerable people in society. Same with face masks, social distancing, etc.