I do a lot of mentoring and coaching. Very roughly, 60% of people respond well, 30% struggle but have some improvement, and 10% don't respond at all. I really do think 90% of people benefit and change at least somewhat from coaching.
However, there is also a correalation between how difficult/toxic a team member is and how well they respond to coaching. At this point I think if a truly difficult team member responded to coaching, they probably would have stopped being difficult earlier in their career, because someone else would have told them to knock it off.
The only thing I've seen work there is being embedded into a culture that uniformally corrects the problematic behavior, and even that is a crapshoot.
However, that doesn't change my experience that most people do want to get better and do respond to help.
However, there is also a correalation between how difficult/toxic a team member is and how well they respond to coaching. At this point I think if a truly difficult team member responded to coaching, they probably would have stopped being difficult earlier in their career, because someone else would have told them to knock it off.
The only thing I've seen work there is being embedded into a culture that uniformally corrects the problematic behavior, and even that is a crapshoot.
However, that doesn't change my experience that most people do want to get better and do respond to help.