You may be THE expert in your field.
You may know more about your topic than just about anyone.
But still... be humble.
It might be hard to be humble when you're really good at something. You might want everyone to know how good you are. You might feel the need to be recognized for your vast talents and knowledge.
Just remember: Without the audience, there is no speaker. Without an audience, you do not exist. You need the audience as much as they need you. Never forget that.
So keep improving, keep honing your skills. Keep focusing on being the best you can be and paying attention to the audience's needs, wants and interests.
Instead of worrying about whether everyone knows how great you are, think about putting that energy into making the audience feel special, feel like you're there just for them, feel like you appreciate and care about them and are giving them your absolute best.
If you want to go far in your career or as a speaker, humility will take you farther than arrogance.