I disagree, with caveats. There's the idea of a "T-shaped person": A little bit of knowledge in a lot of things, with deep knowledge in one area. This is what organisations tend to hire for.
The wildcard person eventually develops into a shape more akin to the differencing mark seen in heraldry for first-born sons. Much broader and deeper general knowledge, and several areas of very deep knowledge.
As one of these people, I can stand by the fact that, yes, you will be sought out by organisations which are struggling with serious challenges, but that does not mean that they can't pay good money. They can frequently pay very good rates, if you're working as a consultant, because you'll be paid for out of CapEx.
You are getting into a metaphor I saw here on HN some years back: "The Paint Drip" model of skilling.
The more you paint over a spot, the more it drips as paint accumulates. The things you spend the most time on, have the longest drips. Some may be in a T-shape, but as you say, there may be many longish drips in a person's skillset.
For the first 10 years of my career, I was more T-shaped. But also pretty good at jumping in and figuring things out.
I'm now a lot more "generalist" - I just tell people, "Try me; who knows what I'll know or be able to figure out". I still have some of those really long drips in my paint drip chart, a few really really long, but the nature of tech means that at some point, some tech you learned really well is dead and you'll never need to use it again. Such is life!
>"Try me; who knows what I'll know or be able to figure out".
This mindset is usually highly toxic in workplace. At minimum it's a nice way to get yourself branded the official a-hole smartypants of the company.
Toxic, perhaps for me. In that if I see something not getting done and I cannot get anyone to do something about it, I will try and handle it. I learn a lot along the way, but at times have too heavy a workload as a result.
The wildcard person eventually develops into a shape more akin to the differencing mark seen in heraldry for first-born sons. Much broader and deeper general knowledge, and several areas of very deep knowledge.
As one of these people, I can stand by the fact that, yes, you will be sought out by organisations which are struggling with serious challenges, but that does not mean that they can't pay good money. They can frequently pay very good rates, if you're working as a consultant, because you'll be paid for out of CapEx.