According to most personality tests, some of the population is plagued with this 'decision making anxiety'. I am one of them. As soon as I hit 'send' when I'm writing I start wondering what I should have changed, and telling myself that someone else would have done better.
It's the single reason I don't follow through on a lot of my ideas. I'm just not confident they're good enough. And the truth is, most of them probably aren't.
But I don't want to let that stop me. After all, Thomas Edison learned several thousand ways not to make a light bulb. And then, he made one. The whole world is benefiting. That little voice just told me "You're not going to do anything that stupendous."
I just told it to be quiet, because I'm typing.