single word requests - What do you call a person who prevents his/her own progress?

There is a psychological condition that affects some people in such a way that they prevent their own progress. They fear to advance. They fear to progress and compete. They might even try to achieve high goals but often get stressed out and withdraw just before reaching the finish line and become losers. They fear their own heights, as evidenced by their probably pervasive acrophobia in the physical world. However, they justify their frustration by saying they don't want to compete and create frictions. They find it hard to try to secure something that others don't have, simply fearing rivalry. They find it a challenge to get involved in something aimed at bringing them to a better level in something, however small that hop might be, so they enjoy doing trivial and fruitless repetitive jobs. There is probably some kind of inferiority institutionalized in them that they believe in and subconsciously think they don't deserve more, making them see little achievements too much for themselves.
Thus, in short, is there an English term (either noun or adjective) to describe a person who prevents their own progress, out of mental disorders, bad past experiences, bad upbringing or whatever?