The rest of us just say that we are an 'X' programmer when applying for a job that requires the 'X' programming language, and then during the interview mention that we also know a bunch of other languages and know how to use the correct tool for a problem ;)
Not at first. But work with people you like and respect, and learn from them. Then ask them when looking for your next job.
Any place worth working isn't looking for the absolute best candidate for X at any cost. A good fit with someone with a good work ethic who wants to learn always works out better than just raw expertise. And a reference from someone you both respect is the fastest most reliable place to find them.
> Any place worth working isn't looking for the absolute best candidate for X at any cost
That's so true. If they absolutely need the best candidate, they are about to run a very risky project.
Good management means, among others, to ensure that new people have the opportunity to learn and to "get into" the project. If management requires the "best" developers, it really means that the management is bad and the developers are supposed to make up for that.
(Having said that, there are also people who are simply a sunken cost. That is, managing them requires more resources than the value they produce. However, that's the other end of the scale, and a separate topic.)
Whenever I hear this, I find I don't recognize the world the poster lives in. Is it a thing to tell coworkers when you're looking for a new job? If not, how many jobs do you need to have and leave before you have a big enough network for this to be a viable strategy? How do you get those jobs?
It really depends on the co-worker and the culture of the company. Sometimes I would tell co-workers, sometimes I wouldn't say anything because I was concerned they would leak that to management and I would be asked to leave before I was ready.
I have found user groups meetings a great place to network though. Everyone is helpful when someone says they are looking, even if it is that persons first time at a meeting.