Not sure if I am exhibiting a communist side here but immunisation is really about population health more so than individual health. The odds of an individual getting the flu are relatively low, you could go your whole life without getting it. But the chance the flu strikes a population is high. If that population has a low resistance ie. not vaccinated then it is more likely to spread and then any individual in that population are at greater risk of contracting the flu.
I am reasonably fit, healthy etc. and so are not in any particular risk group but I have contact with many elderly people etc. who are at risk of severe morbidity. I see it as my role in reducing the risk to these people as much as benefits to me.
Also lets face facts golf clubs are full of elderly people who are at risk so shouldn't we all consider vaccination.