The narcissists never do that.
They make promises about what will happen in the future.
When it (doesn't) happen in the future, they don't say that they let you down or that they were in error or even admit that they agreed to something ahead of time.
In drawn-out cases there will be many deadlines, the narcissist never owning up to missing prior deadlines.
When challenged, the narcissist will create an emotionally hostile situation to cause an immediate distraction, again promising something soon, and never return to the original claim.
Agreed. "I won't prove that I'm Satoshi anymore, but I am". It's getting more and more like religion -- we don't get to know for sure, we have to believe now.. And I'm sure a herd of idiots will do just that.
Sounds like B.S. to me, but who tf am I to judge?