While there's a perception that incels are ugly, socially awkward nerds, the one's I've interreacted with online (and off) tend to be angry, misogynistic douchebags.
The nerdiest guys I know (IRL) all have significant others. The bitter guys I know (two) IRL are older, have let themselves go and have nothing "going for them". They are both very active online however. This is my personal experience, anecdotal of course.
It's an appealing message for a group who sees their intrinsic or essential power impotent in a changing world. It means that radical self-growth, a long and difficult process, doesn't have to happen, painful self-truths don't have to be addressed, and basic skills like empathy don't have to be cultivated. In short, issues can be externalized.
that is, they fell ill with depression because of lack of relationships, entering a loop of ever-furthering isolation and depression, which made them bitter and undesirable.
Some "ugly, socially awkward nerds" somehow find meaningful relationships and get saved. Others don't, and go down the nasty road.
A little bit of empathy wouldn't hurt.
My teens and twenties predated the term "incel," but I was horny, lonely, and unhappy about it, and I could identify with a lot of the online whining from men who felt the same way. I did some venting in the "woe is me" vein on Reddit. But in my real life, at least when I wasn't in a depressive episode, I was always trying to improve my situation by bettering myself and buffing my social skills. I was always thinking of ways to crack the problem. When I felt defeated and discouraged, I'd complain anonymously online, because I knew nobody in my real life wanted to hear it, and then I'd get back to work figuring out my life.
I have no evidence, but I would bet that the perception of the incel phenomenon is warped by a small number of angry people who managed to inflate their importance by expressing the frustration and humiliation of a much larger group of men who are like I was, who go online to express temporary (though possibly recurring) feelings of hopelessness. As an identity, being an incel doesn't have much to offer. It's about a desire for sex, but it doesn't offer any path to sex. I think the vast majority of horny, frustrated young men who have applied the label to themselves at one time or another probably spend much more time thinking about how to be more likable to women than they spend thinking about incel ideology. And if they get any reward at all from trying to improve themselves and their empathy towards women, that will be a better deal than they get from the incel camp.