Once they reach sexual maturity (around two years of age) male lions are cast out of their pride by Dad and are forced to live without the help of the pride, usually for several years. Until they are fully grown and large enough to take over a pride from another male, male lions are nomads and really, can only depend on themselves and perhaps their coalition of other males, most of whom are also just as inexperienced and naive. For this reason, most male lions die within a few years of being prideless. Think about it: while lionesseshunt strategically together, male lions are usually on their own.
This means they have less chance for success (and therefore, they’ve wasted precious energy), and a much higher chance of injury. It also doesn’t help that while they are nomads young male lions are constantly walking through other pride’s territory. At such a young age these males usually stand no chance in run in with a full grown, angry male lion. And the older males will find them and will attack them if they are in his territory. Sometimes the older male’s will simply chase them away, in those cases it’s good to be lighter weight and spry — it up’s their chance of survival — but in most other cases they attack and kill or fatally maim the younger lion.
So why don’t male lions hunt? Well, they do and they can, but it almost feels like justice that they get to reap the benefits of the lionesses work after so many years of living the hard life. Remember, lionesses usually stay within the pride. Of course lions don’t really care about justice. In reality, male lions of a pride have better things to do like monitor territories, protect the boundaries, and some even have multiple prides to look after. After all, they’re bulky and heavier and not exactly nimble butterflies. When it comes to hunting the lionesses have it down to an art form.