This is hardly a new concept, and it's been expressed in public before. I can't imagine the missing element for approaching these issues like a civilized society is that we neglected to frame it in terms of future costs. I can only speak for America, but a big part of the problem here is that, culturally and politically, we don't trust expert knowledge, so things that are counter-intuitive are political poison.

For example: In the case where housing programs for the homeless actually directly _save_ the gov't money, the only argument against them is "I'm taxed enough already!!! Stop giving my money to people who are homeless because they deserve it!!!!". Telling them that, empirically, it's far more likely that the state is saving money from doing this is useless, because "facts are just another opinion" is a disgustingly prevalent belief around here.

through reduced spending on homeless-related law enforcement and emergency medical care, and this doesn't even include the indirect economic value of lower crime and higher property values