Your argument about the cost, "its only 15 B2 bombers", is fatally flawed.
The cost of the B2 is enormous. It was/is justified by it backers as a
necessary deterrent in a dangerous and unpredictable world. Your personal
opinion non withstanding that argument was sufficiently compelling for a
majority of the population and has become more so in the wake of 9-11.

What argument do you have for a colony that is as equally compelling to the
majority to the majority of Americans? The answer is currently none, which
is why we have bombers instead of bases.