Being a leader is not what a lot of people think it is. There is a certain romanticism that many people associate with leadership. They think it means being fearless, in-charge, and the ultimate authority within a power structure. Thus, leadership tends to appeal to people who enjoy power. Often that results in leaders who wield said power unwisely, which results in the company and the leader crashing and burning.
Just as common is the unwilling leader: the leader who has their leadership thrust upon them by their organization with zero say in the matter. This person is selected to become a leader because of good work they have done, or because of their loyalty to the company with little attention paid to whether or not they would actually make a good leader.