> Perhaps the only reason why flu is harmless is because we don't fight it?
Without providing any evidence that viruses tend to become more dangerous when we combat them is anti-science. It's like saying: What if the earth is flat?
Consider successful viral eradication campaigns like smallpox or polio. There's no indication that smallpox became "super smallpox" as it was about to be eradicated. Nor is there a reason to think this would happen based on what we know about how viruses work. It's pure fear mongering on the basis of nothing at all.
Edit: There's so much wrong with the original post here. Not only is the flu sometimes deadly, as others have pointed out, but we already fight the flu with seasonal flu vaccines. Indeed, they seem to have a strong protective effect[1]. The flu doesn't seem to be getting stronger as a result any of this.