The short answer has been around a long time in one form or another.
Good leaders (managers) hire people smarter than themselves and don’t feel threatened by people who are better at given tasks.
The people you hire tell more about who you are than just your leadership style; they are a reflection of your MAP (mindset, attitude, philosophy™) and your confidence.
No matter what the reality, the more insecure a leader/manager feels the weaker the people he hires.
At lower levels, you find that those less willing to delegate rarely hire people with skills similar to their own.
Just as your friends reflect your thoughts, attitudes, beliefs and prejudices, so do those you hire. If you want to know who someone is, just look at who they hang with and who they hire, but not who they date and marry.
All bets are off when love/lust enters the picture.
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