It used to be looked upon as a grave sin, I think it was high up on Dante's seven circles of hell.  Dante puts the usurers in the lowest sub-circle of the seventh circle of hell, with others whose sins are regarded as doing violence against nature and nature's God; many people have noted that usurers are placed deeper into hell than violent murderers, violent suicides, blasphemers, and sodomites. Dante regards usurers as perverting art, i.e., productive skill, by means of which we are supposed to produce and create and thereby imitate the goodness of God. Usury is the anti-art: it produces nothing substantial, being just a set of multiplication games with money, and therefore does not really contribute anything to 'earning one's way and furthering humankind'. It merely gives the illusion of doing so, and is therefore a sort of mockery of both human reason and divine providence -- indeed, a sort of universal violence against neighbor, God, and one's own reason, an extraordinarily efficient form of violence by which you do the most damage with the least effort.