If Bitcoin crashes when any single person sells a billion dollars of bitcoin at once, then what is the true valuation of their ownings after the 'this is too large to cash out' problems take their cut? What is the true value of
anyone's holdings?
This is often not a problem for fiat currencies, they have an entire financial sector dedicated to buying and selling a billion dollars at a time. They are slightly demanding from a regulatory perspective, relative to Bitcoin, but they also do usually try not to crash the currency and they do sometimes get it done.
So I consider that ability to cash out a billion dollars at once a direct spot-check measure of Bitcoin's financial maturity. If this is actually possible to transact at all, then it proves something competitive and positive about Bitcoin, even if it's as much about currency exchange and financial instrumentation businesses as it is the blockchain. I think it is unavoidable that we'll evaluate this through a real-world event, what with one of those exchanges having IPO'd recently. I'd just like it to be an intentional test rather than a surprise, from someone who isn't trying to destroy the world, but does require detailed financial records and a written declaration of insolvency in order to forgive payment.