"we cannot determine per se which fields are guaranteeing the best ROI."
-- The Market will determine the best ROI. If society, in the form of the market (both business intersts and partisan intersts in the fields of arts, music, literature, and "non-applicable" sciences) say that there should be less money spend subsidizing Psychology, is there any reason why we SHOULDN'T spend less money subsidizing psychology???
"Stephen Hawking works on topics that are as zero-ROI as they come. Yet, he is a shingle for Cambridge. Which enhances the reputation for the institution which creates other non-tangible assets."
-- And Cambridge pays for Hawking, not the taxpayer. So, Cambridge IS getting a pretty sweet ROI on Hawking. The same goes for American intellectuals.
Oh, and another thought: What about the ultra-philanthropists, like Bill Gates, who donates over $1B to charity every year? He could fund the education of a thousand Hawkins if he wanted (and get a return on his money too!).