Fear of failure and the fear of success are interrelated, but not the same.
Fear of failure is the fear that you will fail, and feel bad, and others will point out your mistake, and that they will think that you are a failure, and then you will feel even worse.
Fear of success is the fear that if you succede, you now have to live up to higher expectations, that you had to do so much work to succede in the first place, now you will have ten times as much in keep up the pace, otherwise others will think less of you, and you will feel bad, and so forth.
(Yes, both of those sentences are run-ons. Frankly my dear, I don't give a damn. 
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