I think "specialize in something" is terrible advice for a junior but great advice for people with 10+ years experience.
If you're an ambitious junior I do think it's best to job hop as much as you can within reason, like every 6-18 months. Partly due to salary increases, yes, but even more importantly, you learn from having experiences at different companies. No two companies are alike, and working your whole career at one company, even if it's an ostensibly good one i.e. FAANG, limits your exposure. I've seen lifelong FAANG coders who tried to join a smaller startup/scale-up and fall flat because they couldn't adjust. Obviously, job hopping is much harder in the current market, but places are hiring, so it's still worth trying.
For seniors though, eventually the value you provide as "just" a senior developer caps out. A software developer with 10 years experience provides a lot of value over a developer of 1-2 years of experience that justifies a significant difference in pay, but does a 20 YoE dev provide a lot more than 10 YoE? In a general "senior developer" role, I don't think so. For specialized roles, though, you can have a lot more influence, provide a lot more value, and yes, command a better salary. Unless you move into tech management, specialization is how you can keep progressing once you've acquired the requisite technical chops.
oof 6-18 months as a hopper? It are really shitty jobs in my experience if that's the max you can stay somewhere before not learning new stuff.
I'd say that just leave once you are too settled and are just performing tricks. That can be 6 months as you say but also 5 years. Also, never be the smartest guy in the room.
context is everything… I compare generalist vs. “specialize in something” similar to using diversification while investing (index funds) vs. stacking your chips into few things.
no WEALTHY person is all that diversified (e.g. warren buffet) but of you course there are plenty RICH people who are. specialization is high risk, high reward (e.g. have a dear friend making insane money as cobol coder for decades now who couldn’t write a hello world program in any other language) while generalist is safer route but won’t get you wealthy, just rich (which isn’t too bad :) )
