And you could fire him at any time but you don't and you just let him keep fucking everything up, who's responsible?

Bonus question, completely hypothetical of course: this unqualified person's contract expires and, on the way out, he sends a violent mob to disrupt the hiring of his replacement, and you still hire him back a few years later, despite him racking up criminal convictions in the interim and showing no signs of improvement, who is responsible for his continued fuckups?