Anybody can build a twitter at a tiny fraction of the cost of Twitter. The problem is always user acquisition. It's extraodinarily difficult to get a vast segment of the userbase to switch to your platform. Even getting a tiny handful would cost vast sums of money. Think about it. If it could be done, it would be done and we'd see a largely segmented social media landscape with hundreds of twitter clones. It's not the case.
Isn't one exception to this the case when you control both the old and new platform, and can technically just migrate what content possible and just replace the old one with new? It technically does not even have to be "new" platform, it could be presented as "twitter redesign".
Twitter has 450M monthly active users. Elon bought it for $44bn. With ~$5bn in operating expenses, that gives you an absolutely insane CAC of $90 to play with.
