I'm over 40 and I've been continuing to get more work than I can handle by staying up to date on my tech skills. Maybe that professional headshot I never got would help, though.
In my experience older devs really fall into two categories with a pretty sharp division between them. One group has continued to learn and keep up with their skills. These developers are extremely skilled and experienced and can in many cases be far more productive than younger developers with more shallow knowledge. What they lack in appetite for workaholism they make up for in ability to do more with less work and…
How do you know this? Have you been in a good position to evaluate the performance of many older devs? If so, how much diversity in languages/environments is in your sample?
Most of the negative attention I've gotten from younger devs in work settings has been in the form of constant interruptions for me to use keyboard shortcuts. 1) It's very disruptive to the discussion at hand. 2) It's never been an actual problem. 3) It's always couched in impatient and negative emotional tones. 4) It makes it harder for others to follow what you are doing, if you are always concentrating so hard at going fast. 5) It's always seemed like a pointless attempt by young people to seem like fake hackers on TV.
Chris Granger famously observed that programmers who said "I never use the mouse" use it about 50% of the time they're actively programming.