Cowards can't be kings.
Cowards are violent and treacherous; it's not the armed man you need to be wary of, but the man who wishes to disarm.
The cowards admits up front that he is weak. Believe him. He will become deranged with fear. He will panic and lash out. Execute the loser before he makes a mess.
Not that non-cowards exist these days.
Perhaps you could say democracy arises because there are no kings which could maintain a kingdom.