Many people point to CSPs already running negative cash flow and ask how on earth CAPEX can keep growing from here.

It is a foolish question.
Look at what Arvind Krishna (IBM CEO) said in a podcast conversation.
“Year one of enterprise AI is a net loss. That is exactly why 80 percent of companies right now look like they have failed. It comes down to more engineers, higher token costs, and opportunity cost.
Year two is precisely when the 10x return kicks in. Most companies are not failing at AI. They are simply at the worst point on the curve, right before ROI compresses and improves.”
Ultimately, at this 10x return inflection point, the CSPs’ own revenue base will be expanded by AI, so even as CAPEX grows in absolute terms, the CAPEX to revenue ratio will decelerate, eventually setting off a virtuous cycle, a flywheel effect.
Why do people look to the future when judging CAPEX, but look only at the present when judging cash flow? Cash flow should also be judged by pulling forward the future cash flow.