Why associating with spiritual life/God calls for austerity
In general, people are under the impression that spiritual life means voluntarily accepting poverty, which is not true. A poverty-stricken man may be materialistic, and a wealthy man may be very spiritual. Spiritual life does not depend on either poverty or wealth. Spiritual life is transcendental. Consider Arjuna, for instance. Arjuna was a member of the Royal family, yet he was a pure devotee of God. And in Bhagavad-gita (4.2) Sri Krishna says, evam parampara-praptam imam rajarsayo viduh: “This supreme science was received through the chain of disciplic succession, and the saintly kings understood it in that way”. In the past, all kings who were saintly understood spiritual science. Therefore, a spiritual life does not depend on one’s material condition. Whatever a person’s material condition maybe – he may be a king or a pauper – he can still understand spiritual life.
Source: A.C. Bhaktivedanta Swami Prabhupada (2014 edition), “The Science of Self-Realization”, Page 76