Competing with the authority bitwarden the company has over the bitwarden open source project. That's just the first thing off the top of my head. Very few people go to the competitor offering the exact same thing but with less say on the popular codebase.
That already somewhat exists.
Reimplementing the server side is the easy part.
But a commercial offer will need rebranding the client, and maintaining forks is much more involved. As long as Bit warden publishes the sources ...
Competing with the authority bitwarden the company has over the bitwarden open source project. That's just the first thing off the top of my head. Very few people go to the competitor offering the exact same thing but with less say on the popular codebase.