Profit-Motive and Usury

The existence of laws against Usury implies that there is a threshold at which Interest becomes harmful.  Furthermore, the variability of that threshold indicates its arbitrariness.  Hence, it is even possible that 0% is that threshold, i. e. that charging any Interest on a loan is harmful.  Now, the comparison with an Interest-free loan shows that the only motive for charging Interest is Profit for its own sake.  Thus, implied in the acceptance of a law against Usury, is the recognition of the inadequacy of the Profit-motive as a fundamental principle.  For, implied is that 'One should seek Profit' is not unconditional, and, hence, does not account for all behavior.  Furthermore, the arbitrariness of the threshold, which does not preclude the possibility that it be 0%, implies that at least some of, and perhaps the entire system that Smith bases on the Profit-motive is Vicious, a possibility that is clearer from the identification of the Profit-motive and Greed, a Vice in many Moral doctrines.  Nevertheless, Capitalists seem not to recognition that their acceptance of constraints on Usury entails constraints on Profit-seeking behavior.