Devotees are materially impoverished because they use everything they have, not for themselves, but for Krishna’s service. Srila Prabhupada does not necessarily mean that we have to live in complete poverty; rather, to be “materially impoverished” means to live with the mentality that “nothing I have belongs to me.” As soon as we think something belongs to us, we become thieves.
LFD Vol 2 Pg 261, 2nd Paragraph