Life is too short to not be working with decent people.
That being said if you have the opportunity to work with some people who have been in tech for 20 or 30 years - become their buddy - you're more than likely to find out they are some of the smartest out there. When I was first out of college I worked at a place where the 2 guys I sat next to were 40 and 50 years old - they still are the best mentors/collaborators Ive ever had.
(a) Ding! I had to drop out of college to support my parents.
(b) Ding! I stuck around with jobs that made my physically unstable and emotionally depressed because otherwise I would have been unemployable.
I was originally an iOS dev, which I love, and I hate Android programming, but I've been forced by circumstance to get reasonably good at it over the past two years. And yet to some of the people I know, I'm the "old" guy, and I haven't even hit my mid-twenties.
If that's the case, it speaks to the immaturity of some of the people you know.
"Narcissists hate being around young people because it reminds them that, once upon a time, they used to be young and able to do the sorts of things that narcissists cannot do on the weekend anymore."
This completely ignores the evidence directly in front of us that all good engineers will one day start looking older and start having a lot more trouble finding job offers.
I don't really understand how you go directly from saying that it's unintentional and is "unreasonably harsh age-grading, coming from an inexperienced and privileged set of people who've never had to do grunt work" but then proceed to (try to) explain how it's perfectly logical that you can have a positive outlook of the future of your career, but actually you're going to have to take what you can get, which is the reason why "premature decline is far more common than it should be".
Maybe I'm missing the gist of your argument here? Are you suggesting we should be doing job interviews on a curve, excusing 20 years as a code monkey at some place you've never heard of because they probably had a mortgage? I don't know if that's your point, but it is definitely off base here: those 20 years might have created a middle-manager toady or they might have honed razor-sharp gut instincts and experience with relevant languages and tools. Either way, walking in with the assumption that "premature decline is far more common than it should be" means you're probably going to miss the truth of the matter, which is the whole point. No one is suggesting affirmative action for greybeards, they're saying that the kinds of things many in tech assume because a person has grey in their hair means that they don't get a fair shot, even when their experience is extensive and applicable.
It's not about the money once you have 'enough'.
Your job description skills matter, but only if you also are a functional alcoholic who is addicted to playing online games for 30+ hours a week in addition to working 60+ hours a week.*
Startup is Mother. Startup is Father.
* I write this out of bitterness because I don't drink or play video games, which oddly I feel disqualifies me from working many places. "Oh, you don't play xbox? That's okay, I guess. The entire company gets together for six hours on Friday to drink and play marathon games though."
Sure you can game in moderation, but if you do so you won't be a gamer. I think I average maybe a handful of hours a month playing games, and that is as much as I will ever see myself caring to spend on them. There is no way for me to relate to people who call themselves gamers.
I'm not sure what preconceptions you have about "gamers" are, but from what I know, most gamers are in their 30's and have lives outside of video games.
I wouldn't call myself a "gamer", as per your definition, but I've loved playing video games since the early 80's, which might not register with your experience. I'm an ordinary guy with a beautiful wife and kids. Not sure what your beef is.
I'll play video-games on occasion but to be able to pass myself off in that sort of gamer culture is I think impossible unless you are willing to glue yourself to a television for hours and hours a week.
Other types of "frats" do not need that level of dedication I think.
For me, work is about doing something that produces value for the shareholders so they can afford write me a paycheck on a regular basis. When I've finished doing that, I'd like to use my time the way I see fit, thank you very much.
Ugh I hate that. This one time, there was a few hours to bridge between the end of the work day and the start of the office Christmas party (presumably because some management guys had to drive back from out of town). The other programmers quickly set up a multiplayer Starcraft game and later an FPS deathmatch. I quickly found out both types of games are not a lot of fun unless you possess a modicum of skill in them (unlike, say, Tetris or 1000 Blank White Cards).
So maybe it's not the narcissists are limited by age, but rather that age limits narcissism.
To be fair there are exceptions. There are people who just enjoy programming for the sake of programming and building stuff. These programmers will most likely never be out of date. If you're not one of those people, then you need to force yourself to step out of your comfort zone and try to use something new at least every year if not more often.
Then again, I think some of it is subconscious and unintentional: unreasonably harsh age-grading, coming from an inexperienced and privileged set of people who've never had to do grunt work and therefore have slack-free careers. People who are young and have high career efficiency ratios expect a linear trend-- consistently improving projects-- but the reality for most people (save privileged 22-year-olds) is that they have to take the work they get, rather than being able to focus on their passion or highly-visible (e.g. open source) work. I, personally, would love to hire someone in his 60s with no slack in his career-- I'd make him my personal mentor and figure out how he did it-- but it's quite rare to find such a person.
The reason ageism exists is that most people have to take low-quality, career-toxic work to (a) avoid income volatility that becomes more unacceptable with age, (b) evade the "job hopper" stigma, and (c) remain employable without moving to another city every 3 years, and this creates a world in which premature decline is far more common than it should be.