Perfectionism is the belief that a person lives in a perfect world and based on this belief he expects everything to go perfectly in his life.
A perfectionist might expect:
That he should never make mistakes
That everyone should love him
That he should always get straight As
That he should always succeed
That he should never be rejected
That all people should be kind and loving
That anything good will be appreciated right away
That being talented means that he will succeed at the first attempt
While a normal person would strive for straight As or full marks he wouldnt feel that bad if he missed a mark or two. A perfectionist on the other hand might feel really down If he missed few marks.
A normal person would feel bad when rejected by one person this feeling will go when finds that other people still love him, a perfectionist on the other hand would feel horrible if only one person didnt like him.
How perfectionism affects self confidence
There is a well known psychological theory called the expectations disappoints theory.
The theory states that the resultant mood a person experiences after an event is the difference between his expectations and the outcomes he got.
For example if a man expected to begin his life with 8000 Euro starting salary he might feel bad if he started with 7000 even though this is a very good starting salary.
Since a perfections expects everything to be perfect he faces disappointments all the time , these disappointments doesnt only make him feel bad but they badly affect his self confidence.
Each rejection makes them feel unloved
Each failure makes them feel incompetent
Each mistake makes lowers their self confidence
Each success that wasnt 100% perfect makes them feel like losers
Because perfectionists expect to be treated in a perfect way everything that disappoints them affects their self confidence right away.
After all if a perfectionist believes that being perfect is an essential requirement for being worthy then he will feel worthless if he didnt manage to be perfect.
Living in a such an imperfect life perfectionists keep losing their self confidence bit by bit until they feel completely worthless.
The other draw back of perfectionism is that it never makes the person feel satisfied after doing something even if he has done it well. After all self confidence is all about trusting your abilities and skills but if each time you do something you never feel that it was good, how come can you feel confident?
Thats why perfectionists never feel confident even though the main reason they try to be perfect is to feel good about themselves,