As a manager/supervisor/mentor, I've coached more than a few people to success to know that I'm actually objectively good at this. Quite a few people I've worked with have gone on to be extremely successful in what they do. And I like to think I helped them on that path a little. But there are exceptions to this where indeed I failed to get people off their ass and improve themselves. A handful of those situations escalated to the point where letting them go was the next logical step. Some people are just fundamentally hard to coach or even open to being coached.