I would’ve been inclined to agree with you as of 10 minutes ago, until I read this Wikipedia article saying Starship refueling will require 10 or more launches. Damn, that means at least $1b to leave LEO assuming each launch is around $100m, so not really all that much cheaper than expendable stages.

https://en.wikipedia.org/wiki/Starship_Propellant_Transfer_Demonstration