Money making schemes should be easy; we cannot divert our attention for money making activities. We require some money for prosecuting our activities, and if we get that money by contribution that is best, otherwise, we can sell our literature and books, etc. But if we direct our attention like others, then it becomes karma. And karma is very dangerous for persons who want to go back to Godhead. Therefore, in Bhagavad-gita karma yoga is advised.
Letter to Hamsaduta, 21 June, 1968