I’m 40, all my significant career growth was after 30 with most of it after 35, I’m more employable now than I was 3 years ago and am paid well. I was really worried about a Logan’s Run-esque slaughter at 40 and I’m not seeing it, with the usual caveats on luck and anecdotes. I do believe there is intense ageism in our industry but I think it may be endemic to certain areas or companies. Don’t fear the reaper my friends, you can be 40 with a family and still work in high profile tech, probably.