You're doing a really good job of evading the point here.
If your friends are making $100k/yr, they are squarely in the same hiring demo that 40 year old senior devs are.
The whole thesis behind the article you are commenting on is that companies are hiring young because young devs are cheap. You made a comment to the effect of, "watch out, young cheap people can be domain experts too". I think you're mostly wrong, but I'd love it if you were right, and I'm very much putting my money where my mouth is.
I know that there are anomalously capable 25 year olds out there. I'd love to talk to them, too. But the idea that all of Silicon Valley is built around those people rings false. It may very well be built around 25 year olds, but not the weird ones that run High Frequency Trading Engine teams.