I wasn't really talking about the transferability of C++ knowledge to other languages. The amount of effort to learn C++ is greater than the amount of effort to learn most other languages. Whether that knowledge transfers to other languages is another matter altogether.
The amount of time to become a C++ expert is far greater than to become a Python expert or a Go expert. After spending a few years learning C++ spending a year learning Go doesn't seem like a big deal, so why not learn it?
I just don't agree with your statement "If you're really good with C++ you'll figure out most other languages fairly easily".
As I was trying to illustrate there are a wide range of language features available in other languages that C++ does not have anything remotely like.
It takes a long time to learn C++ not because the concepts are particularly hard, but because the implementation of the language is rather messy and the code you produce can easily do crazy things not apparent on the surface.
The amount of time to become a C++ expert is far greater than to become a Python expert or a Go expert. After spending a few years learning C++ spending a year learning Go doesn't seem like a big deal, so why not learn it?