Even if the vaccine does not completely prevent the particular strain of flu that is circulating, the antibodies it causes your body to produce can still provide some protection. That means you might still get sick, but the disease will not be as severe. And that difference in disease severity can make the difference between life and death.
The absolute worst case scenario as far as flu goes is when a strain starts circulating that most people have never encountered. Then, they have no residual immunity to it. That is when the flu is most deadly. That's what happened in 1918.
I’m sure what you say is true. I only have opinions; you have actual knowledge. It’s a personal preference. I won’t get the flu shot. To avoid getting or spreading the flu, I’ll stay out of situations where it spreads. That’s to the point of being pretty much of a hermit in the winter, doing my necessary errands first thing in the AM before there are many people around.
From what I’ve read, the 1918 flu killed mostly young people who had the strongest immune systems.