What do all these people have in common?

G. Washington, A Lincoln, W. Churchill, R. Kroc, M. Twain, C. Dickens, E. Ferrari, S. Jobs, B. Gates, M. Zuckerberg, L. Shing, T. Turner, J. Glenn, J. Rockefeller, H. Ford, S. Wozniac, and N. Tesla

-They all never finished school-