My husband got a flu shot once decades ago and it was the only year he got sick with the flu! Right after, and really bad. So he refuses to get a flu shot and hasn't had the flu since. His metabolism is different than most people, though. For example, he is allergic to sulfa drugs.
I have never gotten flu shots and have had the flu only twice in the last 40 years or so. I think I don't have as much exposure to the flu as most people, though -- no little kids in the house, don't work in a place where sick people congregate, etc.