You are estimating the average Starlink customer at 1000 USD/year? That seems significantly above average mobile and landline Internet fees, so it would seem hard to acquire 20 million customers while competing with those?
Apparently the average phone bill is 80USD/month. Again some of the highest in the world. https://www.moneysavingpro.com/cell-phone-plans/comparing-us...
edit: what I was going for is, you can't take that number and extrapolate it to the whole world