If you look at just the satellites, the build + launch costs are about $2.5M ea, which is impressive to be sure. But they only last <5 years[1], so that's $500k per year replacement costs. Then if you look at their capacity, they still can't meet their FCC / RDOF broadband designation speeds, but let's be generous and say they can serve 1000 simultaneous users per satellite (their current ratio, let's say it's good enough, incl. oversubscription ratio). So that already means 50%-100% of the entire monthly Internet bill from a consumer is going to just be replacing satellites. Let alone everything else to be an ISP.
This is very basic math. They need to launch more satellites if they want to hit their RDOF throughput goals and serve customers in the remaining areas. The most valuable extra-rural areas were low hanging fruit.. the future addressable market is more dense and competitive suburban areas, which further limits the number of users per satellite because users share the spectrum of a spot beam in denser areas.
Now some point to recent pre-IPO articles claiming "$8b profit" but they're grossly misleading by calling EBITDA a "profit". EBITDA only tells you that Starlink makes money on a satellite once it is already in space and connected to a user. It deletes the entire cost of building the satellite, launching the satellite, the user equipment manufacturing, and just about all other substantial expenses. Not to mention payments servicing all their debt and Starship development.
[1] 1-4 starlink sats burn up in the atmosphere every single day! https://planet4589.org/space/stats/restar.html