A funny thing often happens when you first become a manager (leader). You think that you became a manager because you had all of the answers or that being a manager requires knowing all.
After you settle into the role and if you have the right mindset, you realize that your job as a manager/leader is to find people who are smarter than you and help them produce at peak levels; essentially you are there to coach and remove roadblocks. You cannot truly be a great manager until you put your ego aside and realize that you become worth more with a strong team.
Now by smarter, I don't really mean straight IQ, though it could be. Smarter means better at doing certain things than you; you can't do everything yourself and it is not your role to do everything anyways. Set the objectives, give guidance where required and then step back and let your team succeed.
Make it easy for your team to approach you when they are stuck. Don't pretend you know everything or talk down to them. Ask the right questions and let your team find the answers if possible, or provide a sounding board or gentle guidance and if necessary bring in the right resources. Admit you don't know everything.
When you first start teaching your students, they are beginners and you are the superstar. Then they start getting better, some faster than others. Sometimes the student will exceed the skills of the instructor.
Sometimes an instructor will hold knowledge back so their students will never be better than them. This is not your role as an instructor. It is caused by petty feelings like jealousy and personal insecurity.
Making students who are better at something than you is the ultimate compliment to a master instructor.
When your student becomes the master at a particular skill, or your team members are better at something than you the manager; your true role is just beginning.
Many top performers require someone who has "enough" knowledge about their area of expertise to understand them, but more importantly, someone who knows them and how to nudge, prod and encourage the best from them.
This is the role of a coach or mentor; or great manager.
Great managers normally brag about the accomplishments of their team members; not themselves. They succeed when their team succeeds.