I don't think you understand the term "poker pro" correctly. At some point, if you really want to become a poker pro, you should ask yourself how much do you make with your job and compare that to your earnings with poker, over certain period of time. And then you decide if you "should" keep your job and still play poker as a hobby in your free time, or you fully dedicate your time to poker.
My guess would be that you don't have to read any books to gain big earnings, though you would need a lot of experience. Watching others play, replays of hands, scrolling through forums and stuff that aren't books are all excellent choice of knowledge.
Despite that, I think that there are things in books, that will change your view on poker and help your poker game
more than other stuff. That doesn't mean the first line in a book will change your life, but one particular sentence/advice could help and improve you more than anything else have, until then. I value books very highly, and respect their content.