A young friend of mine was just let go from a job after four months. Things had started going badly fairly quickly and her boss was acting irrationally. Turns out her boss has not had an assistant last longer than four months.
Why are senior management and HR not doing something about this?
If this woman were so valuable to the company that despite her atrocious management and people skills she was necessary, then take away her staff and let her partner with someone who can manage. But chances are she's not that valuable or irreplaceable.
Everything has an opportunity cost, and the one associated with turnover is huge. I speak from personal experience. It takes time to hire someone, and then you have to train them and if done right, that takes time too.
If you have someone in your team that needs to constantly be hiring, you should start asking questions. Provide them training. If that doesn't work, either move them to a position where they can't do damage or replace them.
Doing so is actually in the best interest of the company—and your bottom line. Having a bad manager not only effects the morale (and perhaps health) of this person's direct reports, but also everyone else they associate with. And every time they've got someone quitting and or being trained, they'll become a bottleneck for the rest of your team.
Part of a manager's job is being able to manage. If they can't—and a good indication is high turnover, unhappy employees, and/or low productivity—then they have failed at their job.
Have you fallen victim to this? How has your company reacted?