You don’t have to hate managing to not want to be a manager. You also don’t have to have a huge reason for declining a title. Sometimes it’s just simple. Knowing that a bigger role would take you away from your strengths or the parts of your work you enjoy most is enough of a reason and it’s valid. The brave choice is knowing when to stay exactly where you are.
And if your work matters, if you’re growing, contributing and bringing your best to it, then you are not failing. You’re just refusing to be rushed into a version of success that doesn’t match who you are.