How to these pattern of thought and behaviour arise from just a single belief about the fixedness or growth of ability and potential? Well, consider the implication of the belief that your abilities are fixed.
You can never become more intelligent, or more attractive or more competent. You will never increase your musical ability, improve your social grace or become a better leader.
If you truly believe that this is the case, at least on some deep psychological level, why bother trying? After all, if you believe that traits such as your intelligence, skill or competence are fixed, why bother trying to improve yourself or move forward?
There is no point; nothing can be gained, because everything is fixed. As a result, opportunities are never taken and potential is never cultivated.