If you are young and healthy, I don't think they are pestering you for your sake, but to build immunity and prevent its spread. Healthy people should really look at flu shots as a kind of duty to their fellow citizens, who may be more vulnerable.
It's recommended for anyone with frequent contact with children.
Oversimplifying, it is recommended for people with more than 65(50) years, people with chronic diseases or HIV, and pregnant women and babies from 6 month to 5(2) years. Also people that work or live with them. But each country has it's own rules and recommendations.
I stopped getting the flu shots in my 20s because I would always get sick despite the shot. I was convinced in my mid-30s to start getting them again. I still get sick, but it's not as bad as when I skipped the shots.
(I know at least a couple times I ended up getting the shot that prevented a variant that we didn't get. There's enough of a time gap that the shot isn't causing the symptoms.)
[1] https://www150.statcan.gc.ca/n1/pub/82-624-x/2015001/article...