everyone regardless of age is at risk if they come in contact with an infected person. Infected persons are not distributed uniformly. Therefore risk in non-uniform. We don't know in any particular situation what the risk is, we can only estimate what the risk is on average. The risk will go down significantly for everyone if roughly 60 some percent of the population or more get vaccinated. Below that number the benefit to the unvaccinated, on average, of others being vaccinated, drops. if only a small percentage of the population get vaccinated, those many that don't gain, on average, practically no reduction in risk. The advantage to going past the magic number, somewhere between 60-70 % vaccinated worldwide, is that there is then an excellent chance of the covid-19 virus virtually disappearing. How ever if too few get vaccinated, then we will remain subject to future flare ups. Everyone who can get vaccinated should. It's the the smart thing to do; it's the right thing to do.