Do you take up extra classes or courses for your business?

I have come across some persons who have never taken classes or even extra courses since they started their business. They feel they already know all that they need to know since they are doing well. Have you ever once taken classes or sign up for some extra courses to improve yourself in your business?

Every business person is a constant learner. I regularly take classes to get to know more about my business. The business world is evolving in every sector and any business person that fails to update his knowledge and methods regularly would be left behind.