To answer your question more directly, perhaps a reasonable place to draw the line would be where all inherently capable individuals have a fair chance at gaini

To answer your question more directly, perhaps a reasonable place to draw the line would be where all inherently capable individuals have a fair chance at gaining or fulfilling their (reasonable) dreams if they so choose. Government subsidies generally are supposed to exist with the goal of the greater society in mind. Hence, the line must allow persons from poorer backgrounds to get whatever education is necessary in that particular society to have the potential for upward mobility. A caring society would not let health, education, or other barriers of upbringing stop people from working their way up, should they possess the ambition and inherent potential. Naturally, of course, as the education (or knowledge) barrier to entry for employment grows ever higher, there will presumably be a greater proportion of society that is naturally unfit for work. Hopefully technology is able to keep up with the growing load of unemployed persons so that society as a whole can still progress.