In my experience, a true expert is not the guy who throws out or uses what he has on his DD214 as his primary credential, or any other "I did this or I was here" or is the first to speak up of how to do something. They usually just let their results, skills and total package of experience do the talking for them.
Next time you're in a class or group of people or with more than just a couple folks notice the person who generally is one of the quietest or is just standing off a bit, is either a complete overwhelm novice (but you can tell by looking at them) or a true master who is being a humble observer or student. Masters generally are very polite, humble, patient, and they have a tremendous about of depth to them. Wanna be's and entry level experts are superficial and quick to jump in and want to save the world or help.
I am not an expert at anything but I know several actually. And when we attend classes together, they have a motto...keep your mouth shut and your eyes, mind, and ears wide open. If the instructor is full of rubbish they won't say anything but will participate fully with an open mind. Then after class during the AAR they'll start pointing out all the "making stuff up - MSU" garbage the instructor touted and also what they picked up, learned or discovered they are unconsciously incompetent in.
Here is what I'm seeing...folks who graduate from some school or discipline. They come back and by rote try to teach everyone what they've learned. All they are doing is regurgitating what their instructor taught them. They have no depth, no experience, no alternatives, no disappointments, set-backs or been embarrased when things went terribly wrong. These are "Instructor Experts"
True teachers - they have been at this trade/discipline for so long; they've experienced disappointment, setbacks, embarrasement, and seen their friends or students fail because of their shortcomings...they are a full time "humble" student and they have a great depth of knowledge so if one method doesn't produce results another one will. They find reasons to help people succed not excuses for them to fail. These folks are full time students - constantly learning, relearning, and evolving their craft. These folks are true experts. Usually true experts don't see the limelight...although it can certainly come to them.