I mean if you value a company for its future cashflows, how long will Starlink be the only game in town? Will we not see other rockets/space-internet competitors in 2040 for example, in 15 years from now, from any other company (or even, any other state actor)? I think we will, and I think that timeline is generous. Without a monopoly you're competing the price towards marginal cost to cater to a tiny and shrinking fraction of the world that needs satelite internet. The vast majority of people live in urban environments, particularly among those who can afford internet in the first place, and it's only growing further in that direction.
I think Starlink is a wonderful product but there's a reason it has $10b revenue, while telecom companies around the world do more than $1.7 trillion in revenue.[0]