Here's a question: for a decent frontend developer who's still far away from the "master" level he describes here, is it worth chasing mastery or might it be better to branch out to other skills, like management?

I think I'm a solid frontend developer, but I'm a few years professional experience away from the level he describes here. I know my way around HTML, CSS and the various browser quirks - though I'm still learning the idiosyncrasies he describes here. I've written a ~10000-line app in Angular.js, but my Javascript code is still sloppy, and is nowhere close to my knowledge of Ruby. I'm gradually picking up the basics of design and UI as I go, but that's a whole other mountain which I could climb for years.

"That guy I offered that car to (not really) took a job at a startup and he’s the guy. He’s THE front end developer for their product which doesn’t exist yet. He gets to point to that thing, a year or two from now when it’s worth a bazillion dollars (I do wish him luck, after all) and say, “I did that.” There are people out there, right now, who get to point at Twitter, Facebook, Gmail and Google Maps, at the Iphone’s UI, at Github, at the YouTube player – stuff used by millions upon millions of people – and say, “I did that.”"

Thing is, few products are built by one superhero. I'm wondering if, rather than transform yourself into a magical-unicorn designer/hacker - it might be better to get solid at development, solid at design, but aim to only get good enough that you can manage people who are better at you in those areas?