1) Older programmers won't put up with bullshit. They expect to have reasonable goals, be listened to, be compensated fairly, and have a reasonable schedule. They've been around the block enough to identify bullshit and will leave when it starts getting too high.
2) Older programmers really don't always understand the "cool" social crap that teenagers are into this year (for good reason--most of it is garbage). Unfortunately, most of what Silicon Valley is interested in is "cool" social crap so that they can get a big buzz and flip the company to Google or Facebook.
Funnily enough, companies that value that silly thing known as "profit" are quite happy to hire older programmers. It's just a function of Silicon Valley not believing in profit that is causing the ageism.
It seems everyone these days is a "founder" of something. I own sites that do things these youngsters can't do (Turn a profit) but I've never, not for one moment ever thought I was a founder of something great, just trying to earn a living!
I agree with the companies that believe in profit thing. Once you strip out the happy clappy, social crud employers just want people who can help them turn a profit.
I do agree that I am way more experienced, knowledgeable, and have a much more healthy and mature perspective on business and software engineering than I did when I was 22.
You are a year or two from being 'old' in this mad market.
Is there a list of companies which value profit so the people who complain about the "problem" (from companies most likely to not be around after too long) can go work for them?
It would certainly match up with my experience in London, where it seemed that a lot of the programmers over the age of 30 were working for large, established finance companies. The age of programmers around the 'Silicon Roundabout' startups tends to skew a lot closer to mid 20s.
This derails in reality because you'll have companies making money but bullshitting their employees to save most of it.
You don't need the best of the best programmers to have a shippable product, and even if such a company is only mildly profitable, keeping the profits at the top makes it a good place for stake holders.