Doesn't that depend on circumstances? I don't work. If I go to a movie or a store, it's early in the day when the air has cleared and it's not crowded. I've figured out a really good diet. I have plenty of liquids. I don't go into overcrowded places with bad ventilation.
I figure I've cut the risk of getting the flu (which is never 0) down to less than the risk from a flu shot.
Yes, but if you get sick in a pandemic, you may need to go to a hospital or it may be very difficult to avoid coming into contact with infected people. This is perhaps an outlier risk, but I don’t think the probability is insignificant.
The risk of getting complications from an infection rise dramatically as we age. Our immune systems can become compromised by other diseases (e.g. type II diabetes, COPD).
You have to judge the risks. If you are in good health, get good nutrition, and are physically active, then you may be able to get by fine without the vaccination.