Claiming to be an involuntary celibate makes about as much sense as claiming to be involuntarily friendless or unemployed or, for that matter, born. To the extent it's bad luck, no one gives a useful damn; to the extent you have a role in it, it's on you to make needed changes for different results. Employers aren't obligated to give you a job because you need one; friends aren't obligated to find you worth spending time with because you're lonely or unvalidated; life doesn't owe you frictionless validation and self-actualization and compelling wonderfulness with no tactical or strategic effort on your part and with no need for resilience; women don't owe men mind-blowing gorilla trampoline sex just because some guy wants it or fantasizes about it; perhaps more to the point, women don't owe men worshipful gratitude for mediocre sex from scrawny little whiners. (And that cuts both ways, ladies).

As others have pointed out it evidences a sense of entitlement to have sex as some kind of inherent human right and that the most likely explanation for a woman's disinterest is some feminist plot to hold out on men in order to control them. When in fact (1) we men don't need sex or our balls will explode, and we don't need a woman for sexual release, either, so the only harm they're really complaining about is they don't have the power to take what they want when they want it so they can have the social capital / bragging rights; (2) to whatever actual extent women have been socialized to have a tendency to use sex as leverage or some sort of cudgel in a relationship it's only because they have no other power base, because of historic and structural patriarchy; (3) women need and want sex too, so that couldn't be the whole story in any case.

Someone articulated it quite well for me already: "The defining characteristic of self-identified “incels” is that they feel entitled to sex. They believe that women OWE them sex and they do not see any reason why what a woman wants should prevent them from having what they want. It indicates objectification and dehumanization of women, extremely stunted emotional development and a total lack of empathy."

Crybabies playing victim.

Instead of taking responsibility for their own behavior, they blame women for their inability to attract women.

It's a pity people are stripped of their humanity when they are labeled.

That no one wants to have sex with them for very different reasons than they claim. What's funny is they've just switch places with nerds who could never get laid.