Natural selection is a resourceful tinkerer and could have rewired men's brains to respond to lowered testosterone in any number of ways, not necessarily by becoming less competitive.
Natural selection might have made women's brains appreciate a man with high testosterone.  
mnli hypothesis: Natural selection might have made women's brains appreciate a man with high testosterone.   premise: Natural selection is a resourceful tinkerer and could have rewired men's brains to respond to lowered testosterone in any number of ways, not necessarily by becoming less competitive.