It's perfectly OK to have a personal project that only you yourself work on. In fact, most free software projects are like that. A project with only one contributor, or only a couple, can be quite limited however. A larger group tends to get more done and, more importantly, they do different things. A more diverse group brings in more points of view which tends to make the project better suited to a larger group of users.

Attracting contributors to a project you've started can be tricky. Your humble author asked on Twitter and Mastodon for advice on this very topic, and wrote up a summary on his own blog.

The condensation of the summary is:

Get people over the hump of making their first contribution, by making it easy and removing all unnecessary obstacles. Make contributing into a rewarding experience.

Obstacles can be things like making it difficult to install, run, or use the software, making it difficult to find, retrieve, or understand the source code, not having public discussion forums (mailing lists, IRC channels, etc), or not having a public ticketing system.