Basically, men aren't as important as women. If 99.99% of men died today, the human race could be back to it's normal population within a generation (a man could easily father a child a day for 30 years ~10,000 children). On the other hand, we'd have much more trouble if 99.9% of women died, since a women can only realistically have about 10 children in a lifetime. This encourages men to be bigger risk takers - women were the limiting reagent to population growth.
Similarly, the potential gain for a ridiculously successful man (genetically speaking) is that he can have several thousand children. A women, on the other hand, can likely have 10 children whether or not she is successful; so there is little (evolutionary) benefit for her to be hugely successful (or take risks necessary to do so).