Agoraphobia, fear of failure and defeat, is a greater hindrance to success in the stock market than is greed. But in the stock market there also seems to be a fear of success. I can't put my finger on the precise reason it exists, but it does.
All too often investors are snatching defeat out of the jaws of victory. I see it all the time and I'm sure it's happened to you, too. You sell a stock for no real good reason and then it goes on to be a gigantic winner. Or you are so intimidated by the market and losing money that you simply sell with the crowd over and over again and console yourself for the short period of time when that same stock is a little lower, but feign ignorance or even take it off your screen once it's roared back.