I think there is something here.

While software developers get better with time (and if you're smart that never stops), the need for people with 25 years of experience is minimal. Assuming that they've kept up to date, those people will do a job better than someone with 10 years experience, but probably not massively and probably not enough to warrant a higher salary. After all, a bulk of commercial software development simply isn't that difficult - it's CRUD apps, data processing and automating dull repetitive jobs in a way that saves money.

I think part of the skill with staying employed as you get older is to ensure that you aren't simply looking for work which justifies your massive experience as if you do you're going to be fishing in a very small pool. You need to accept that some (maybe not all but certainly a lot) of the work you're going to do is work that could be being done by a less experienced developer and adjust expectations (including salary) accordingly.

  I think part of the skill with staying employed as you
  get older is to ensure that you aren't simply looking for 
  work which justifies your massive experience as if you do 
  you're going to be fishing in a very small pool. 

Heck, a coder with 30 years of experience isn't even likely going to outproduce some offshore rent-a-coder in the short term.

Which is fine, really, because like you said: a bulk of commercial software development simply isn't that difficult in any technical sense. A lot of times it comes down to integrating various disparate systems and managing people (as well as avoiding pitfalls we learn to avoid over time) and those are places where somebody with experience can really shine.

Older coders should really work on people skills. Even if you're still an in-the-trenches coder, as you get a bit older, people are going to expect some leadership. Even if it's just some informal guidance of other team members.

The 20 year-old coding away with his headphones and never talking to anybody on is potentially charming; a 40 year-old doing it is just weird.

I have experienced old developers clinging to methods and techniques they learned 20 years ago. That profoundly affected their productivity and code quality. E.g. one guy, who originally started with C on UNIX. Even when he was coding C++ or Objective-C, he would use \0 terminated char[] instead of string objects often. This lead to bugs (e.g. UTF-8 not working, because he assumed every character is always one char/byte long). There also were memory leaks all over the place.

> While software developers get better with time

Good developers may get better with time or stay the same. Average to poor developers might get worse.

As with other people who are starting out, you've got plenty of time to plot a course. Remember to add to your skill set when you can.

To me at least it reads as a bit unfocused. You've clearly got a mass of experience but for any individual job much, if not most, of it isn't relevant. It's a CV that says "look at all the experience I've got" but doesn't really do a great job of saying why you'd be good for any specific role.

I'd look at three or four resumes, each more focused around a specific skill, industry or problem type. Maybe one as a hardcore Linux developer, one with a more web / multimedia focus and so on. Pick out three or four projects relevant to each one and write a few lines about them. While the fact you've got 35 years of C is impressive and maintain your own Linux distro, it's not going to be relevant for roles focusing on a higher level language and is just distracting from your abilities which are relevant.

Also, personally I'd put it on two pages and space it out far more. Larger font, larger borders, more white space generally.

TL;DR: You're probably better than 90% of devs out there but you're not selling it well. Overall aim for less content but with more punch and make it nicer to read.

It badly needs trimming, I found it hard to get a sense of your skills (and which are current) that you want to work with.