permanent space colonies will be of little benefit to the US gov't and its citizens. Especially, when the residents of such colonies are no longer citizens the mother country.
This is of course untrue. Militarily, industrially and culturally, offworld colonies done right (permanent, aimed at self-sufficiency, and large scale) would provide immense benefits for the sponsoring country. And, sure, someday those colonies will become their own nations. Would the US be better off if the Moon becomes "the nation Luna, formerly the US colony Luna" than if the nation of Luna is formerly a *Chinese* or *Russian* colony?
As with colonies in the "New World," the mere existence of distant offworld colonies will provide *all* kinds of benefits for the homeland. People living on Ceres, for example, will be interested in advanced propulsion systems and nuclear explosives in a way that the people back on Earth won't be. So when a comet is detected heading towards Central Park, who's going to have the tech to deal with it? And once again... will the US government be better off if those Cerean colonists speak some language other than English and have no allegiance to the US?
The US government *should* be devoting one percent of the federal budget specifically to exploring, claiming, colonizing and exploiting every single accessible corner of the solar system. There's no good reason why, centuries from now, "the United States" can't be spread from inside the orbit of Mercury to the Oort cloud and beyond. If interstellar travel ever becomes practical, there's no reason why the US flag can't replace those fifty stars with a stylized galaxy. Would you rather have the United Federation of Planets be based on the US Constitution, or the dictats of the Holy Russian Putinate, or the fatwas of the Interstellar Caliphate?