The high valuations are essentially lottery tickets, not something based on any sort of calculation of discounted future cashflows. The bet is that the researchers working for some of those frontier AI model companies will come up with innovations that give them a sustainable competitive advantage that goes beyond just purchasing more compute and licensing more proprietary training data. Obviously they can't all succeed but perhaps one or two will get lucky, perhaps by figuring out how to greatly improve efficiency or something that isn't easily copied.