People organize themselves into hierarchies. I'd say this isn't because of any biological predisposition, but because hierarchies are the most efficient power structure for decision making among large groups of people. This is only because the alternative of weighing everybody's opinion equally is chaotic, and prone to poor decision making due to lack of education and experience among an entire set of people. Look at any election, and the consequences of letting everybody have a voice become evident (that said, there are other tremendously good qualities of elections that make us keep them around).

Leadership is the ability to make decisions on behalf of the group under you that are good. It's seen as being altruistic because it can enhance, or detract from the quality of work, and the quality of life of everybody beneath you. The effect of good decision making is multiplicative based on how great the scope of your 'leadership' is. A good decision maker in charge of 100,000 people will therefore bring a lot more productivity and positivity to society than a good decision maker in charge of only 100 people.

Moving forward by replacing 'leadership' with the term 'decision making' - which is really what it is - there are a lot of individuals who have consistent history of good decision making. These individuals exemplify good decision making far too often for it to be a function of luck or random chance. Of course, there are definitely some people who got lucky and were mistakenly labeled as 'good decision makers' (lest we forget November 2016). I'd also say that because we don't live in anything remotely close to a meritocracy, some people achieve leadership and management only because they come from a position of privilege in society. Nevertheless, the concept of good decision makers bearing great importance in society should not be dismissed, because historically the human race has excelled, or completely grinded to a halt based on how, and who we let make decisions.