While they may not be ideal or people living in Urban areas, they also aren't limited to selling to people who are physically connected by cable like a regular ISP would be.
I think you're underestimating the market here. Especially on the enterprise side when you start thinking of things like airliners, cruise ships, etc...
Starship is trying to get launch cost down to $10 per kilogram to low earth orbit. At that cost it is not clear to me that cables are better except for short distance point to point backbones. One other issue with cables is regulation or monopoly.
At a time when state actors are becoming increasingly non-cooperative, it may not be wise to put all your eggs in someone else's basket.
Launching a starlink satellite costs $1.5-2M per satellite for the current design. Each satellite lasts around 5 years and they need 42k of them.
Do the math and you get $13B to $17B per year ignoring inflation and ignoring the massive ground infrastructure that is also needed (costing billions more per year).
Residential plans range from $55-175/month and will make up almost all subscriptions. Most people will get the $85 middle plan, but we'll round up to $100/mo or $1200/yr.
Breaking even with no profit requires 10-15 million subscribers.
As starlink claims to have around 12k subscribers and just 10.5k satellites, I'd guess the system is profitable.
The cable question is still compelling though. Rural fiber costs around $25k per mile. This means that an average $15B/yr buys 600,000 miles of installed fiber every single year.
My conclusion is that the ideal solution would be Starlink keeping total satellites closer to the current 10k number ($4-5B per year) and spending the other $10B/yr running fiber to new areas.
Their subscriber base would drop as new fiber got installed in rural areas overlooked as "not profitable enough", but stabilize at still profitable enough from travelers and truly inaccessible places.
There are people whose current behaviour/situations will happen to benefit from this, and that may be a niche, but seems like there's a really solid chance many more people actually will change their behaviour in response to this being available. That's how disruption happens.
To be honest I can easily see the default changing if the service is good enough. I mean it seems like you basically get most of what is good about wired plus a whole load of extra previously totally unavailable benefits. For a price, to be sure, but that'll come down.