This is all true and good advice. I'd add to this that as a survival strategy, one can develop the meta-skill, of being able to spot which tech skills are fads,

This is all true and good advice. I'd add to this that as a survival strategy, one can develop the meta-skill, of being able to spot which tech skills are fads, and which "have legs" (will be around for a long time). Anything from a specific vendor, you're at the mercy of what that vendor does, corporate takeovers etc. Whereas open source things are a lot better. There's also the idea that stuff that's been around ages, is likely to stay around ages, whereas new stuff you may not know yet. My vim (originally vi) skills, command line and sql have served me well iterally 32 years. Not really changed that much in that time. Python has done me proud for 20 years and no sign of going away. json and git probably here to stay. Ones to avoid are the likes of javascript frameworks. Some stuff fashionable on HN probably not gonna stay. Back in the day, *nix , usually Linux, was a brilliant investment. Unfortunately the waters have got muddied now by running in the cloud which has vendor lock-in. I do a lot of AWS these days, with a niggling concern that Amazon can totally change this and pull the plug when they feel like it. If you work in a large corporation which wraps tech in their own internal tooling, that can be a problem , causing you to get de-skilled. So, something else to avoid.