How much does believing in yourself matter?

How much value do you give to believing in yourself in terms of winning a chess game or winning multiple chess games?

U already know after ten steps into the game

Much value. But fake confidence won't help either. If you reach a certain position you are familiar with and where you can say "I can win this" or "I can draw this" it certainly helps a lot and the result will be what you said.

confidence in ones abilities could be the difference between successfully overcoming a difficult situation and wiining or giving up and losing.

"You miss 100% of the chances you don't take"

So yeh, it matters a lot.

Not very

It matters after losses; believing that you can learn from your mistakes or bad habits will get better results.

idk but I think controlling your emotions helps a lot. not panicking when you make a mistake and playing the best possible move in the unexpected position you now find yourself in.

If I miss that my opponent can put me in check, for example, and get put in check unexpectedly, sometimes I panic and make a quick move to get out of check as quickly as possible, like the length of time I'm in check matters.

It all depends on which 'self' you choose to believe in... don't believe in the arrogant self; the perfectionist self; the timid self; the complaining self; the robot self...perhaps chess is a vehicle for discovering the ' core self... believe in that.

I thought I might have something useful to share but it's probably wrong so I'll just keep it to myself. Hope that helps.

It depends in what you believe, am I really a 2000 player? Or 2500 player? Or very good, you have to believe that you have some chess talent, if you don't you will get bullied in many games, confidence is part of the game. If you go into a game thinking this guys going to crush me, it will be a self fulfilling prophecy, if you allow yourself the possibility of winning, then awesome things can happen.