Now, let's omit that for a moment. Let's say that after having implemented your language after years of work, now for some reason you got 1 prospect user.
That person will ask you about: syntax highlighting, linting, code navigation, testing, packaging, documentation, operating systems/architecture support, etc. Who is going to contribute all that if you are busy writing everything by hand?
Unless you have as much time as Terry Davis, you are better off starting by piggybacking on something that exists. Then, once you have an idea that scales, you can convince other people to help you and have a successful project. Then you can have a viable ecosystem that people can comfortably join.