I don’t follow why merging with SpaceX means they don’t have to pay for their existence. Someone does. Presumably now that is SpaceX. What is SpaceX’s revenue?

Maybe the idea is that SpaceX has access to effectively unlimited money through the US Government, either via ongoing lucrative contracts, or likely bailouts if needed. The US Govt wouldn't bail out xAI but they would bail out SpaceX if they are in financial trouble.