Last time this annoyed me, I did a thorough look at the Go source code to figure out how accurate calling the language "Go" is. Basically, aside from the mailing lists and bug tracker URLs, "golang" only appears in one place; the ppc64 port contributed by IBM. Everywhere else in the code, it refers to itself as "Go".
I get that these people are not in your circle or whatever, but the term 'golang' appears nine times on Go's own case studies mood board: https://go.dev/solutions/#case-studies
Personally I suspect people more readily adopt 'golang' because all the mailing lists used it as the prefix, the domain was golang (as opposed to go-lang), the official subreddit is /r/golang, and the developers have such a habit of prefixing things with 'go' (as in GOPATH, goroutines, etc). I used to believe it was because there was another programming language with the same name, but I never did find examples of its use in the wild, so I'm no longer sure that affected anything.