Not OP, but I think there are two main reasons for this. Firstly if
you are a professional you probably only had time to teach yourself what you needed for the job at hand. This is a great skill in and of itself but by definition it favors practice over theory. Secondly, if you're self-taught that means you didn't have a mentor and likely you don't know what you don't know. It's impossible to study topics you've never heard of, or whose connection to your field you're unaware of.
As a self taught person this lines up with my experiences and it depresses me that I 'missed out'. But I try to make up for it by continuing to learn, I'm just now really getting into Information Theory though and can't help but think how this intuitive understanding would have helped me twenty years ago.
