A NEETcel is either (1) someone who believes that their status as a NEET is a major contributor to their inceldom or (2) someone who is an incel and also is a NEET, either because they see no point to working (since they can't betabuxx), or for other reasons. Many incels are discriminated against in the workplace for their looks, so it becomes a contributing factor in why they become NEETs.
Some incelists are NEET for political reasons as they don't wish to contribute taxes to a purse which disproportionately benefits normies, Chads and Stacy's r just sex-havers in general. These incelists argue that a large proportion of single mothers who produced children from their wild hooking-up during their teens and 20s eventually become single mothers on welfare. As such, since incels weren't invited to these hooking u parties, incelists wonder why they should pay for the after-effect of a party they were excluded from. To incelists, this makes about as much sense as paying the rent of a random person you don't know, halfway across the world. Others have chosen the NEETcel path out of misanthropy, and subsequent unwillingness to engage in a society they feel has rejected them.