A pauper is someone who relies on government welfare or who does not make enough to cover basic needs (food, clothing, shelter), depending on who you ask. Many incels in incel forums relay stories of homelessness or poverty. It is likely most incels are NEETs, homeless, or otherwise individually poor.
Relationship to inceldom
Women do not show sexual interest in paupers largely. A side effect of this is that women do not house men, but men generally house women, and thus pauperdom is mostly a male issue. Arguably, most male paupers are paupers due to inceldom. What is certain is that more men are extreme paupers than women and inceldom is the main cause of the gender imbalance in pauperdom.
Criticism of definition
There is debate whether or not to call adult NEETs, welfare recipients, or really most of the American non-homeless-poor as paupers. The argument is that a better term might be grifter, as these groups typically have all their basic or immediate needs met. However, NEETs can become paupers through homelessness easily after the death of their parents in the lack of a trust fund or job/social ability.