We need both fighters and drones.

Human self-importance.

We think we're magic, despite the fact we aren't built for high g dogfights at all.

Kind of the same reason us being space colonizers is a pipe dream at this stage in our civilization. We can get a dozen highly trained peak human specimens to grow potatoes on Mars as a symbol, and I'm all for that, but not regular people. One mistake everybody dead, one cabin fever victim in the right position everybody dead. We literally can't even care for the almost infinitely forgiving habitat we evolved out of that's perfectly suited to our biology, and all that would require is stop actively, recklessly fucking it up.