I worked hard to be able to make the tradeoffs that suited me.
That's the most important sentence in this entire thread
True, but its something that's very time dependent. When the job market is good, its relatively easy to take control of your destiny. When the job market is bad its tough to do much more than use the time you have to prepare yourself for better times to come.
You have to be preparing yourself (as best you can) for the future at all times.
Part of that is estimating which few technologies will become important, and not bothering to learn more me-too technologies (e.g. C#, Delphi), nor those with a short half-life (e.g. any web framework, any generic microprocessor family).
Such estimation needs understanding of fundamental (i.e. theoretical) weaknesses of the existing technologies, and understanding how a new technology ameliorates them (most don't, of course, and should be ignored).