Some people can't get vaccinated due to health reasons or they don't mount a proper immune response. They need you to do your part to establish herd immunity.
I'm in neither of those populations but I really don't see why any healthy 18-25 year old would want to life a single finger for a 60-80 year old, after the latter left the former with a broken economy, overpriced education system and an unaffordable housing market. I mean, it shouldn't be on the younger (inherently politically weaker) generation to re-establish inter-generational solidarity... (You can see the effects of this even pre-vaccine - youngsters partying while oldsters arguing for lock-downs.)
That confuses generalities with specifics. The 60-80 year old that you infect might be someone who agrees with you and worked very hard to oppose those things.
I suspect the number one reason is that most 18-25 year olds actually love their parents and grandparents, and don't want to see them dying an agonizing death from covid.
Clearly this doesn't apply to everyone, but I reckon it applies to most.
