[nsotelo]

I'm not sure it really works like this. Suppose you've spent 10 years becoming a master java developer, and now all the investment is going into python. You're going to better than the boot-campers after 1 week and a master developer after 3 months, whereas the others will still need years to catch up.

I think it's worth keeping a loose working knowledge of all the mainstream software in your field, but don't really go deep until you need it.

[redisman]

People who have only used one language way overestimate the importance of having a decade of experience in one language and way overestimate the amount of time it’ll take them to be production-ready productive in a new language.

Syntax is easy and learning a new approach to language design is a great learning experience. You’ll still transfer most of the good parts over but you’ll also learn that maybe some things you’re used to can be made simpler.