I used to write tests mostly because: "you should write tests.", with poor mental model 'because the best practices say so', with truly not understanding potential benefits

I understood the rule, but not the reason behind it.

Then I did a refactor — and for the first time, tests actually saved me.

Then i realized that, I was wrong, or at least not exactly right but I was missing the crucial point.

The real value showed up when I started refactoring parts of my side project.