The biggest competitor you have in your life is YOU!
If your mission is to shine your light and inspire others to shine their light; why do you get affected by others? If you believe in your mission then ask where is the insecurity coming from?
Perhaps the belief in your mission is not strong and/or you are lacking focus enough in your craft? All this calls for looking inward.
Instead of complaining about others, why not that spend that energy getting better and better and identifying and pursuing your own unique selling proposition (USP)?