At least, IQ doesn't mean someone will behave well. Nor does it mean that they are going to read situations well. I think that if we were truly very intelligent across all of the human faculties, we would have far less issues in the world because no matter what happened, we would slow our thinking down before we act, more often than not. But, unfortunately, we are far away from being that intelligent at scale, so poor behaviours will continue on largely unabated.
Being very smart isn't enough. You also need to have leadership skills. Even very smart people have flaws. These are significant flaws that prevent them from achieving great success. This is why there are so many problems in the world.
A good manager is someone who anticipates problems and finds solutions early on. They don't discriminate between employees and are fair and honest. The same applies to employees.
The problem is that everyone is discriminatory in some way, making preferences over others because of their own beliefs. It becomes much worse when the supervisor doesn't recognise their own preferences.