For those that don't follow Git hosting, it may not be obvious, but GitHub's mind share, is truly massive. If you want to compete head to head with GitHub, you'll basically, have to wait for them to REALLY screw up. If you want any sort of chance, you'll have to approach things, from a totally different angle.
Make code reviews your number one priority. Be the place that people want to put their code in, because they can review code, significantly easier on your site, as opposed to GitHub's. Make management your number one priority. Be the place that can provide managers with code metrics and analytics, that GitHub can't. And so on.
To take mind share away from GitHub, you'll have to treat Git hosting, as a secondary thing. You can't be a derivative of GitHub and expect to compete, and succeed. Like Snapchat, Instagram (before acquisition) and others, you can only compete with Facebook, from a completely different angle.
If you can provide a novel solution, that cannot be easily duplicated by GitHub and others, getting users to store code with you, will be significantly easier. With GitLab, Gitea, Gogs, etc., Git hosting has turned into a commodity product, which means you'll need to focus on providing value based on the code stored and not the management of the code.