Greed is a contagious mental illness without which civilization as we know it would not have been possible.
Fear has always been a very important whistleblower. Our emotion and our history can provoke fear that may arrest us at any time or at any place. Above and beyond, fear might be contagious and its scent, sometimes sensual, sometimes mystical or animal, can exude the musty and arcane smell of destiny. ("One could still feel the smell of fear" )
Who can tell? It may be that there must always be growth - and that if one does not grow kinder and wiser and greater, then the growth must be the other way, fostering the evil things. Or it may be that the life they all led was too shut in, too folded back upon itself - without breadth or vision. Or it may be that, like a disease of crops, it is contagious, that first one and then another is sickened.
It is not about whether you call yourself a leader or not. It is about what you have to show to people as a leader. Leadership is contagious, you carry it and share it.