Because if we don't the Chinese will. Unless we start looking a quarter century or greater down the road we will cede our position as the top power in the world. The explotation of space resources, and its derivatives such as a population more attuned to science and hard education, should be a national priority. Our current status is threatened and I, for one, do not want my country to slip to the ranks of second tier.
Yes, this will entail sacrifice and your tax dollars (mine too), but I'm willing to make the investment for a more robust and secure America.
Oh-oh... something wrong here. ALARM!
May the visions of sugar plums keep dancing in your head.