The diminishing half-life of knowledge

There are those that have resumes tailored to a single particular thing that if hot right now, will have 1000 recruiters after them to run certain grid studies. I'm more of a fundamentalist (need to think of a better term)for my field where I can tell you the underlying math behind most of the studies performed, familiar with the pro/cons of a dozen different application softwares, can code, use SQL, Linux whatever. I'm also a people person, which is helpful as there is a lot of stakeholder interaction. If you understand the equations/theory and how all the technical junk works....there aren't many roles in my industry I can't get up to speed on in very little time, while having a global understanding for how it fits as a cog in the bigger machine. This isn't true of most in my industry unfortunately. Many many only know a single role, have experience with one tool, don't understand the math behind the tools, can't code or do data analysis... etc.

I've found the broad/general experience to be very valuable, but it's harder to convey that to recruiters sometimes that are looking for "X". I sometimes have to tell them that what I have is highly transferable to "X" and that I have a bunch of other goodies their employer would be very interested in. Sometimes it works if they're communicating with the manager looking to fill the role and not HR. If I can actually talk to someone at the company.... usually not hard to arrange, then they've often offered to make a custom role as well. I know it always isn't the same for software shops or large companies with layers of beauracracy, but that's my experience.

Umm, you are just picking survivorship bias tech things.

Focusing on html was a good choice. Focusing on xhtml2 or vrml would be a bad choice.

HTTP will serve you well. FTP or Gopher not so much.

TCP is a better choice than IPX or SCTP, etc.

Ultimately though, i think the point is to focus on the underlying ideas. You should understand transport protocols not tcp specificly, then you can easily apply that knowledge to QUIC or whatever.

But you went on to list a bunch of tools. Sure today HTML, TCP, HTTP seem fundamental, but when they first came out?

CPU is very open ended, what do you mean focus on CPU? Do you mean x86 or do you just mean that there exists a concept called a central processing unit where bits go in and bits come out?

With that said all I have to say on this issue is that there are different strategies to learning, and for some people such as myself, I prefer learning things from the concrete and towards the abstract. I like starting from the actual tools and frameworks and very specific and particular things I can manipulate, and then abstracting from them and building up concepts, as opposed to what it seems many others like to do which is to start from high level concepts.