Self Development benefits society because it allows you to give an informed contribution to decisions making.
Sometimes I wonder why we should bother to learn or to experience because to what benefit it gives. But then I realise the more we understand and know then the more we can make our world a better place.
Self improvement is important to everyone. Not just to the person learning but to the people surrounding the learned person.
Strive for improvement and strive for knowledge because it will help to contribute toward a growing society.