Ignoring the fact that we aren't using money for rocket fuel (that is people are benefitting from us spending that money) the potential upside is immense. There are a time of resources available in the asteroids and a moon base makes mining those resources easier and cheaper.

Because it isn't a free market in the USA. And those that regulate it don't seem to care. Or maybe it is those that have been granted a monopoly do everything they can to retain said monopoly.
Things would be different if we actually had a free market