How can you tell whether or not you will become famous because of your writing?

I often have a desire to write. I love the idea of being like one of those famous authors who have written books that have become bestsellers. I don’t know if I can be like them, though. Is there a way to tell if I can or should I just give up on this dream?

The reason I want this is because I really enjoy writing and I want to make a difference in people’s lives. For example, I like that books like the Harry Potter ones have been such a positive influence in the lives of many children, teenagers, and even adults.

I view imagination as very important and I like the idea of creating a world that several people around the world can get lost in and can share with each other for years and years to come.. with their children, with their grandchildren, with their friends, with their reading buddies, etc.

I don’t want to write some book about someone in a bad relationship that encourages young people to get into bad relationships, though.

Are there themes I should focus on to make my dream come true? If so, what are they?

What kind of name should I use to call myself? My own or a fake one? If a fake one, how do I choose which one to use? Why?

If I use my own name, how can I protect my privacy online with all my Q&A floating about (considering there are people who know my full name who are aware of the screen name I am thinking about)? Am I being too paranoid about that?

Should I take the risk and write, throw myself out there, and see what happens?