Man is a highly social creature, and thus if one wants to be successful at something they need other people. Human beings are not solitary creatures; we live in societies. Being 'successful' means having social status – the ability to command respect from others and authority over them within a group structure.
If you are successful at something, people will respect and admire you. If people respect and admire you they will want to associate with you; thus one can gain a network of social allies in this way.
If you are successful at something, then you can attain power over people – the ability to direct their actions. Thus one can gain a network of social dependents in this way.
If you are successful at something, then people will give you money for it; if people respect and admire one's abilities as a result of their success, they may provide one with 'success money', offering monetary compensation in exchange for continued service to them.
In addition, people will want to be healthy and attractive, since this makes one more successful at getting social allies and dependents. The better one's health the greater opportunity for success in life.
This is the basis of human society. People want to be successful at something, and in order to do that they need social allies and dependents.