In all kinds of species, at all stages of life, males are more likely to die than females. Once males have invested the effort, however, they stand to reap huge reproductive rewards with very little additional effort. Over 83 percent of all male elephant seals ever born die without reproducing, a 20-year study found. But a highly successful male may have over 90 offspring. A highly successful female in his harem will have about ten.
Harems are common in many mammalian species, including humans.
Still, it isn't all gravy for guys. They can try to control females. They can control and gather resources that are useful to females. Or they can display for females, independent of any resources. As a mating strategy, Low observes, it's a little weak.