Because they do job that they love to do. If you do job that is your favorite you will make it very good and will achieve success, become famous. To be famous doesn`t mean to have acquantances among celebrities. I think Bill Gates or Steve Jobs became famous not through friends-celebreties or their appearance.

thanks to give both of you

luckiness,their connections with other celebrities,physical appearance,and very rarely with their skills and cleverness

Are you asking for their motives?