First of all, the F-35's job is to kill people, let's not get overly moralistic here, but of all places, the military is quite explicit about using human lives as expendable resources to achieve military objectives. If the Chairman of the Joint Chiefs is asked to choose between losing 20 enlisted privates in a training accident vs. losing 20 B-2 bombers which one is he going to choose?
For your loved ones it is infinite.
But for a government with X funds and Y lives to save, there has to be a price.
If someone ejects on every little problem, you spend billions more on that and billions less on some other life saving initiatives.
Putting aside the bad ejection survival stats.