The true value prop of github isn't "hosted git + nice gui", it is the whole ecosystem of contributers, forks, and PRs. You don't get that by hosting your own forge.

Also, I wouldn't say GitHub is a corporate attempt to own git... GitHub is a huge part of why Git is as popular as it is these days, and GitHub started as a small startup.

Of course, you can absolutely say Microsoft bought GitHub in an attempt to own git, but I think you are really underselling the value of the community parts of GitHub.