Понимание информации в тексте

Why does the author use the quotation in the final paragraph (“the people who are crazy enough to think they can change the world are usually the ones who do.”)?

1) He shows that high achievers often set goals they are unable to reach.
2) He stresses that those who think differently usually make a difference.
3) He proves that reaching any goal requires a lot of dedication.
4) He explains why high achievers see the world in a different way.