1. I think starlink alone means there is demand for that. Starlink is an appreciable fraction of satellites in orbit... Apart from starlink, satellites spend a lot of money on being as light as possible, at the very least there's a tradeoff here where you get to make the same satellite cheaper by being less mass efficient.

2. I wouldn't dismiss the cost savings from a reusable second stage.

3. They already have experience with legs from Falcon 9, and they're already landing this rocket very precisely with their tower. I would expect the development timeline for legs to be short. Much shorter than the development timeline for human rating the rest of this, for instance...

3.5. Winches and ropes are light and cheap, lowering things to and raising things from the surface doesn't strike me as a particularly difficult problem... apart from maybe the human-rating aspects of the system.

I think Starship has a good theoretical basis for being an economic success. On the other hand I don't have much faith they will successfully execute at this point.

They're massively behind schedule and presumably above anticipated cost. They aren't showing signs of having successfully designed a safe, reliable, and cheaply built vehicle. They've been making what externally seem like stupid mistakes like having their rocket fail in basically the same way twice in a row. They are making political enemies left right and center whether it's by having a fascist CEO committing election related crimes, or littering the same down-range islands with rocket parts from failed launches. They are almost certainly driving away talent by virtue of the same CEOs political roles and crimes, and by virtue of doing things like taking SpaceX engineers and having them work on twitter.