Earlier quoted context omitted.
This also applies to new technologies and skill gaps. I'm over 30, and have stopped following the latest javascript trends. I want younger people to be satisfied with the tools that I learned; they're perfectly adequate. The treadmill of re-inventing the technology wheel also looks like a prison.
The struggle with that is how do you step off the treadmill but stay relatively current. I think about how web pages looked 10 years ago, and in a world of React, I feel like very, very few of the things I learned then help me for more than the very, very basics.
After that, whatever is next on the treadmill is just some new syntactic sugar on top of the fundamentals taught in that book, which you can pick up with a minimum of time and effort.
Occasionally there is something truly new, but those are few and far between.
Also, if you are seriously worried about your earning potential, read this and learn to really apply it, before picking up another Javascript framework: