Elon has stated that Starship will likely be cheaper per-launch than Falcon 9 despite having more than 5x the payload capacity: https://twitter.com/elonmusk/status/1258580078218412033 (Guessing this is primarily due to reusability of the second stage, which Falcon 9 lacks.) So even if everything else fails to pan out Starship could still end up being extremely profitable just by dominating the existing launch market.

That said, I agree that some of Elon's longer-term goals in space are somewhat more questionable from an economic perspective. Safety is still a big question mark when it comes to tourism and intercontinental transport, and a lot of the other proposed uses (such as Elon's goal of settling Mars) have questionable economic value. Will be interesting to see if any new markets get created by Starhip's record low launch costs.