nah you start by faking it and being ironically confident until you trick yourself and it becomes second nature.
replace self deprecating humor with god complex humor until you believeeeee
Because it's effort and not everybody is up to doing that work for one reason or another. We all have self doubt and it takes a lot to push past that sometimes
True confidence is the assurance that who you are is good enough, not that you're perfect and need no improvement, but that if you're doing your best to respect other people that you deserve the same.
If your "confidence" changes based on how others treat you, then it's not truly self-esteem but rather pride and ego.