It’s really all about defining what “success” means. And “Ambition”. I’ve always looked at “ambition” as a negative trait, at least among my peers in the workplace. Someone who is ambitious will not hesitate to step on me if it gets them further up the ladder. But someone who is happy in the role they have, and doesn’t always have their focus on the next thing, will be a much better team player.
That doesn’t mean having no goals whatsoever, or never learning anything new. But it does mean establishing your own goals, that bring you your own fulfillment. And if they don’t coincide with what your boss wants, that doesn’t make you a bad person, it might just make the job a bad fit.