Part-time job/business versus Full-time job

I've been working in Dubai near ten years now, I could say that my salary is just enough for me and my family. Where I am working now is my third company since 2005. I believe it's a good company but still we are not well-compensated because of loads of work and a lesser salary. Before, I am very devoted to my work. I never even thought of applying to other companies. Sad to say, now I am thinking to look for a new job. One thing more is, I am doing a part-time business now. I joined a European-based company with a very small investment (AED399 or $108), and I am earning already a hundred folds. I seldom sell their products, I am just sharing it to others to at least try the products. I joined this business because they have 50 branches worldwide (meaning - stable), and I see that I have future here. This triggers me to resign my job in a corporate world soon. I even enter the world of real estate/properties at present, and I am earning real good for selling condominium (flat) to Filipinos and other nationalities. Now, I see myself where I belong. I am sure, corporate world is not really for me. Sometimes, we are giving 100% of ourselves to a company that never compensate our dedication. I may sound unfair, but oftentimes, they are more unfair. They can not blame me if that 100% of my dedication goes down to around 80%-90%, because my part-time gives me double of what I am earning for a 10%-20% effort I give in my free time only. I guess, the company should take care of their employee as their own family.

Do you think it's unprofessional to have a part-time job while you're still under contract from your full-time company?