> I think that there’s at least an order of magnitude more “happy L5s” older than 40 at FAANGs

This doesn't match my experience. Can you say which FAANGs?

I think in a healthy company it should be true, but my org at Google (~50 engineers) had one 40+ L5. He told me he was frustrated after repeatedly being passed for L6 promo, and he retired at 45.

The L7+ people (my managers and directors, as well as the org staff+ engineers) were all over 40.

I didn't interact much with principal/distinguished engineers, but I think even L7 is pushing 7 figures nowadays.