What do you base that estimate on?
And actually I think even 10K is a very generous upper bound, really if I were betting money I’d peg it at like maybe 2000 engineers that use golang as their primary language and a big chunk of those are SWE-SRE?
There's just _way_ more Java and C++ than there is golang…
Go is very popular in some niches (a semi-mandate in SRE produced a bunch of it) and not used at all elsewhere.