Because you are putting yourself out there and can't predict the outcome. You are opening yourself up to complete heartbreak or complete happiness with no way to know which one its going to be. Talk about scary.
I like to know what the outcome is going to be before I do something. I am not a huge fan of taking chances because I am scared of negative outcomes. I don't like being vulnerable. I'd rather walk the familiar path even if it means being mediocre forever.
But I really want to find spectacular. I want to find the thing that keeps sparking even after the new wears off. To find all that means making myself vulnerable.
How do you do that without being scared?