Age discrimination is absolutely a thing, but (and this is only based on anecdata) I would say it is much, much worse in the valley than just about anywhere else. The rest of the world seems to have a less damaged culture.
My previous job (and my first ever outside NZ) was working for a multinational electronics company in their Moscow Russia R&D lab, a job I got when I was 52.
Compare to Fortran or supercomputers. Was important, isn't much so these days, although is still used.
What I'm saying is that you got on a train that has been running longer than some other trains, hence you meet older people on the train. As someone who has little interest in management I hope to be as successful as you, in this sense of picking long distance trains.