I don't normally read Glamour (haha), but this article showed up on my Flipboard and seemed like a decent write about confidence; I think it was.
"People get scared when you try to do something, especially when it looks like you're succeeding. People do not get scared when you're failing. It calms them. That's why the show Intervention is a hit and everyone loves "worrying about" Amanda Bynes. But when you're winning, it makes them feel like they're losing or, worse yet, that maybe they should've tried to do something too, but now it's too late. And since they didn't, they want to stop you. You can't let them."