Stars don't really do that much, people mostly use it to "favorite" your repo.
That may be technically true, but sadly in reality things are more complicated.
Developers, especially bad ones, use Stars as an argument for choosing libraries or frameworks, for example. Organizations tend to favor those repositories / libraries / frameworks when picking their stacks. People in HR are trained to judge you Github account by the amount of stars that you have. Open Source maintainers who appear popular are often used as poster people for recruiting. The list of ridiculous reasons why stars may matter goes on. Eventually, you will be able to turn a repository with a high star count into money or advancement, because that just how superficial the world we live in actually functions under the hood.