Military spending creates a large number of jobs, allows claims of being patriotic, and hence creates votes. Social programs are very large as well and there is enough spending there as well to generate jobs and create votes.

Space, not so much. Refocus the young from the Kardashians to space and eventually we might sway politicians. For the most part I think commercial exploitation of space is more likely once the money factor works itself out. Then science can hitch rides and have more interest in it as commercial interest increase awareness