I was once told many years ago that the reason fighter aircraft have pilots is as backup insurance to bring the multi million dollar aircraft home if the computers stop working. It was meant as a joke at the time (or maybe not?) but it may be truer today (as long as the fly-by-wire is still working). On the other hand todays fighters are not stable without computer control, so maybe it is no longer true at all, and if the computers die the aircraft can't be flown?

Drones are certainly cheaper and more capable without having a pilot to protect and whose presence limits the max acceleration. However telemetry links and autonomous decision making have limitations also. When drones start taking down F-35's is probably when pilots and F-35's become obsolete.