I think the SpaceX IPO showed them to rent the clusters for billions a month

That doesn't mean they're lucrative, though. They cost tens of billions to build and huge sums to run. Even if I believe that they are now running profitably, that doesn't mean they're "quite lucrative" overall.

SpaceX's numbers show xAI increasing its losses over time. In 2025, xAI lost $6.4 billion on $3.2 billion. In 2026, xAI posted a $2.47 billion operating loss in the first quarter alone.