We can afford it. I know they are thinking about getting one for state of California and few other states already had a smaller version. Mostly made for city itself rather than getting across state or to other state.
I think high speed train is better for getting from FL to NY for example, rather than from one state to Alaska. So, I don't need to think again, especially when we can see very clear that it will boost the economy of US. Tourists, businesses, new jobs, etc.
I know there's a talk going on in NC about having one going from big town in coast to city in mountain area. I just wish they started this long time ago, otherwise I would have traveled around NC more often.
So it's possible, it's just that US had bad tendency to be behind in some area that can be useful to the public for a while now. We are somewhat behind in transportation and communication in compared to other countries. Of course there's some area that we are advanced in.