IMO learning the theories, diplomas, etc. don't make you a successful IM'er. You need to start doing things and learn from your mistakes. Of course you learn from others, but they can only tell you how it works in their specific market or how they've reached success. It doesn't mean you can just copy what someone else does and become successful aswell.
You don't need a degree to become a good marketer. And common sense won't always help either. Some basic knowledge is required, so you know what step to take and what to do next.
You need to profile yourself in your market and your prospects will decide if you're the best or a "me too" wannabee.
I've learned most from watching what others do, trial and error, good times and setbacks...
Andre