I'm a late 20-something working in tech. I recently accepted a job w/ Google (er... Adecco for Google) in SV.
I have read every scrap of reporting on age discrimination in the Valley that I can find. The idea that my age will be a detriment to me in the coming decade is viscerally real for me.
It is also mind-boggling that age discrimination would be going in this direction. In industries like mfg. and oil and gas, the gray beard is a sign of status. I would not be offended at ALL if I was beaten out of a position by an equal candidate 20 years my senior. I'd be honored to have similar qualifications.
Just a single anecdotal counter-point to your stereotype. "They" covers quite a few people in your comment.
https://twitter.com/atxstolenbikes
http://www.statesman.com/news/news/crime-law/police-350-4000...