And the dark side is, ageism is rife in our industry. You could be an expert in language X with 20 years experience and every programmer knows that you could learn language Y easily enough. But you have to convince a hiring manager on the "graduate fast track" who wants someone who knows Y and thinks that anyone who hasn't made manager by 30 is a failure.
You can screw around and play the "rockstar" in your 20s, but it gets harder and harder as you get older, and the number of people able to live this lifestyle in their 40s is orders of magnitude smaller.
Websites are in their own world though. An * expert web programmer has certain advantages. At any moment you can delve into blackhat stuff and make money. I'm not sure what you mean by website technology as always changing so maybe I'm about to say something dumb but here it goes - The syntax changes a lot, sure, but the basic ideas of automation and data work of mining, collecting, and organizing have always been around. Now they are just at the forefront.
* all this really means is you're a good programmer that understands how the web works and knows things like traffic generation, and how money is made on the web. But basically 90% of the real expertise and time is still with actual programming.
As an analogy, think of the Swiss watch industry. There were people there with 30 years experience with the most intricate mechanical devices in the world. Didn't help them one little bit when the Japanese invented the quartz movement, the skills just weren't transferable.
Did you know that, ironically, the British used to be the premier watchmakers, but they were driven out of the market in the 19th century by cheap competition from (amongst other places) Switzerland?