To be completely honest, I haven't read your whole article (read two paragraphs) and only title (it's like those clickbaits from bbc and others) that drove me here, and would like to argue against "hand registering is not investing" title.
Here's a definition of investing, by
Investopedia:
"Investing is the act of allocating resources, usually money, with the expectation of generating an income or profit."
Which clearly states "with the expectation of generating an income or profit". So if you believe that you're investor because spending more money than majority of new domainers, you're wrong.
For example, I just hand registered over 10k in various ngTLDs - .tech being major with 2k hand regs, and spent over $92k in total.
I have already covered my .tech registrations by selling 3 .tech domains, and already in process of negotiating 2 more. All inbound.
Now, a whole point of this title feels like devaluing low budget domainers, why? Because you've been lucky enough to move from that point? Nah.
Hand registering one single .com is still investment, same as buying one valuable .com. It's just different type of risk-taking.
p.s. investing is speculation, gambling and so on. Who can guarantee you that your domain will still worth the same as you paid for 2 years ago? This is nice debate to run, but probably a wrong title and whole POV from OP's side.