Bitcoin, an open source crypto protocol, launched without the existence of crypto companies.
Mt Gox, instead of helping btc, almost set it back years due to the hack.
Bitcoin grew adoption and scale on tor/DNMs and localbitcoins, both of which had organic, non-exchange economic activity which kept accounting in pure crypto vs returning to fiat/needing an exchange.
The attack you’re describing is a 51% attack, and it had yet to happen due to protocol design on the main chains. If it does, I suppose you’d be right.
But I generally think you don’t understand how the tech works and what proof of concepts exist to disprove your opinions, or at least strongly counter your opinions. and without addressing why they’re wrong you have a weak argument.