However, there is a trap, way more insidious then you think, that occurs once a person decides "I know everything I need to learn" or "nobody here can teach me anything new".
The biggest impediment to learning is thinking that you already know everything. The moment you believe there's nothing new to learn, you immediately close your mind to new ideas.
The reason you never want to be the smartest guy in the room, is because categorically that means that you have nobody else to learn from.
This applies to two groups of people, those that take action and those that don't.
You help the group that doesn't take action by educating them and increasing their sense of responsibility towards their environment, thus engaging them and building up their motivation to take action. But this can only be done if the person seeks change it, and doesn't think he knows everything.
Then there is the group of people that do take action, but since they're seeing growth and results, most have decided that they are beyond help since they know everything now.
You must always be open to new ideas, you never know where The next golden idea would come from. It could come from a book, a friend talking to you, or just the thought that you had.
As long as you maintain the mindset that you are the smartest guy in the room, you basically block your awareness from picking up those clues and then using them to your advantage.
The best part about letting go of this belief is that there's no inherent risk or drawback to being open minded and always open to learning more.
In the case of the people that don't take action, I believe that the biggest reason they think they know everything is because they're afraid of taking action and they got used to the sense of security (false security obviously) from not dealing with obstacles all the time such as those that the action takers face.
These people obviously do face challenges, but since they don't have a destination they don't view them as challenges to overcome but just as problems to dissolve so they can go on with their routine of nothingness.
For people who are taking action, the biggest reason for thinking you know everything, is ego. It's that desire to look the smartest, to show yourself and others that you are moving forward faster than those around you, it also stems from a fear of being influenced and considering bad information you might unfortunately get from other people, The fear stems from you not trusting in your ability to judge and discriminate between good information and bad at formation, but between good suppliers of information and bad suppliers of information.
These are the inherent fears that causes people to think they know everything:
Fear of change.
Fear of taking action.
Fear of ego loss.
Fear of bad judgments.
Number one and two are related to people who don't take action, number three and four are related to those that do.
You get rid of the fear of change when your circumstances become so bad that you prefer the risk of change than what you currently have, the other way is for the reward (the goal) to be so big that you would prefer to take the risk and discomfort of changing.
You get rid of the fear of taking action by gradually building momentum by taking small actions consistently and then growing of them until you become comfortable with taking consistent daily action. Rotating the rotor of the boat only works if the ship is actually moving.
You get rid of the fear of ego loss by realizing that the way people around you value and judge you is based on who you are and on your behavior. Having a big ego and trying to impress people by putting them down and showing them how great you are only makes you look insecure, let your habits and results speak for themselves, since that's how you judge most people anyway. Stay humble and always listen, you never know where the next clue might show up.
You get rid of the fear of bad judgment by surrounding yourself with people you trust and mentors you believe in, and also by letting yourself be coached and advised by people you trust and gradually seeing how this helps you, and how your ability to discriminate between good advice and bad advice is a lot more accurate than you previously believed.
You must get rid of the belief that you know everything, until you do you're basically stuck in your current situation and momentum.
Open your mind and listen to everybody you talk to, surround yourself with people you respect, gradually take more and more action, and always keep the reward (the goal) in front of you to remember why it's worth it to keep moving and continuously move faster.
You can use that strategies I gave above, Or you can just find a room with much smarter people than you :-)