It is actually not clear to me if the service will become profitable:
Elon Musk recently said SpaceX needs $30 billion for Starlink to survive[1] (meaning it isn't profitable now).
He also said that they are aiming for 42000 satellites.
And he said, that they are losing money on the Starlink terminals ($500 / unit).
Starlink is $99/month. If a Falcon 9 carries about 60 SL satellites, and they are aiming for 40000 satellites in orbit, that means they need to do 666 Falcon 9 launches every 5 years. That's 11/month, btw.
Even, if reused Falcon 9 launches are as cheap $10 million/launch (I don't think anyone outside SpaceX knows the actual price). That's $6.7 billion in launch costs alone every 5 years.
$6.7B/(60 months * $99/(month*customer)) = 1,127,947 customers
So they need at least 1,127,947 paying customers to cover launch costs alone just to renew the sky-side of the network. That doesn't include the cost of producing the satellites, ground infrastructure (including terminals), bandwidth cost when connecting to the rest of the internet, staff, marketing, etc.
Now, of course, Starship may make the launches cheaper, and 1.1 million customers is not completely unlikely. However, if he already foresee the need of $30 billion now, their costs are probably significantly higher than my estimated launch costs above.
So let's hope we will not be left with an abandoned constellation of satellites that ends up causing the Kessler Syndrome, because SpaceX abandons the endeavour or goes bankrupt 5 years from now.
[1] https://www.businessinsider.com/elon-musk-starlink-spacex-ba...