> sitting on piles of assets like dragons

They (the AI companies) are sitting on piles all right, but not "assets like dragons". Rather, what they are sitting on is piles and piles of debt that eventually will come due to be paid back. The "bet" their CEO's are making is that some "profit angle" will materialize at some point that provides the funds to pay back that debt when the bills start coming due.

> If they haven't saved any money

They have not "saved any money" (not in the sense of a "saving account" in a bank). They are leveraged as far into the future as one can see, and betting that before that lever starts to move they will have a revenue stream sufficient to pay it back.