Don't be passive in your life, or you might wake up one day on the wrong side of 40 and realize that you haven't been in control of your life.
Sorry for the snipe/snark, but... I mean, there's no right or wrong to chronological age. It's not something we have any control over.
My read of age in software is that the age discrimination culture is less severe outside of the Bay Area. I certainly meet people over 50-60+ in Chicago and New York who are still programming and highly respected.
It does seem better in the Midwest. And it's not that bad in New York, although the cost of living is brutal. The nuttiness going on in the Bay Area seems to be a young man's game (and, if you're not well-connected enough to be made a founder out of the gates, a stupid young man's game).
Having said that, I also read the parent's phrasing/remark more as an "observation" of ageism and similar social cut-off constructs that have lately become very prevalent in most professional spheres. So, perhaps they have voiced what they've been observing both around their own lives and within their circles.