Don't fabulate stories in your head that are not useful to you. There is nothing "wrong" with you. The reasons could be manyfold. You could try to figure out why you didn't land a job, or, far more easy and effective, just keep going and focus on what you want, on your strengths, on how to sell yourself. Eventually, it'll work out.
Side note: we developers are a spoiled bunch. 4 rejections and you want to give up on the entire industry?
Side note: we developers are a spoiled bunch. 4 rejections and you want to give up on the entire industry?