Kyle Boatright writes:

I know the comment is well intended, but I've seen some of these people
drive (and eat), and trust me, my flying is far safer than what they do to
themselves on a daily basis.

People say it for all sorts of things, not just flying. Moms in particular
are prone to say it about anything that incorporates even the tiniest
suggestion of risk.

Mostly, I say "Thank you.", but from time to time, I go into a sermon about
how flying is pretty safe IF you don't do stupid things like run out of gas
or fly in conditions beyond your abilities. Then I realize I probably bored
someone or came across too strong and revert back to "Thank you".

Or you gave them new things to worry about: "You mean there are flights beyond
your abilities??"