It strikes me that "incel" and "slut" are related.
Women are shamed for having "too many" sexual partners and men are shamed for not having "enough" sexual partners. Both insults are rooted in the good social functioning of ancient societies.
But it is not currently acceptable to call a woman a slut, while incel is acceptable as a catch-all label for men struggling (for whatever reason) with rejection.
I'm old enough to remember, long before the internet, that women, when gathered together, would gripe about men's behavior. And men, when gathered together, would gripe about women's behavior.
The main difference was that the anger and bitterness that i see today wasn't there. Sure, there were always men who were TOO angry at women, and there were women who genuinely hated men. But overall, it was just a way for both of the genders to blow off steam about each other.
Men often have unrealistic expectations of women. And now, as men are falling behind in education, employment, self-esteem, and overall sense of purpose, it's not at all clear what women should expect of men anymore.
Men today are getting very confusing messages; don't be preoccupied with a woman's appearance, but don't be under 5'9"; be sensitive, but be strong; don't be afraid to date a woman who makes more money than you, but women won't date you unless you make a lot of money; don't "slut shame" women, but don't be involuntarily celibate.
I'm not excusing bad behavior on anyone's part, but let's have a little compassion for all the guys out there who have no clue how they are supposed to act while being unrelentingly demonized throughout the media
Edited to add: one thing men are "excelling" at today is suicide.