I want to write books for a living but that's not a real job
Why do you not consider it a real job?
Because I will not be earning money from it
The odds are against you, but you can potentially make money by writing and self-publishing your books online.  If it's your dream, try it as a hobby while you work another job.
I'm going to do it even if it's not a real job.
I'm glad to hear that you are going to give it a try.  Again, I have to remind you that very few people can earn a living from writing, but you could be one of them.  So hold onto your other job, but try your hand at writing in your free time.