I don't consider myself a professional writer yet I get paid to write. Nor do I think I m a professional gamer and I also get paid there. I am not a professional investor either, but similarly, I do earn. However, I am/ was very good at what I do at work and am able to add value to those around me also - this in my opinion makes me relatively professional - not because of my title, but because of what I deliver consistently.
That shows how reliable a hard-working person should be because there will definitely be a reward for such people someday with their goods deeds towards achieving success which is through hardwork.