I also understand why a man would be "black pilled." I assume these are men who are physically unappealing to women due to factors that are not within their locus of control. Rather than view these has handicaps that can be overcome to a limited extent, they view them as disqualifiers for romantic/sexual interaction with women.
"Comparison is the thief of joy." -- Theodore Roosevelt.
Simply put, black pillers (who can assumed to be sub-6 even after thorough physical optimization), resent that they must be realistic about their league and date accordingly. Relentless comparison to Chad (facilitated by our beauty-obsessed, internet social media society) is the seed of that resentment and bitterness.
A 4 doesn't want to pursue and date women who are 4's. He would rather seethe in resentment and despair that Chad effortlessly brings the 8's and 9's back to his apartment after a night out. This defeatism then extends to the 4's who are within his grasp -- "they all want Chad too." That then devolves into the poisonous sh!t you see on SS sometimes. "It's OVER for [xyz]cels" or "if you're a manlet, kill yourself." I don't have a problem with ugly men resigning themselves to involuntary celibacy. I have a problem with the toxicity they spread to bring others down with them.
Any man, unless physically deformed, can get in killer shape, dress snappily, and become genuinely charming (which requires one to accept, with grace, his situation in life, and find humor and happiness in it). There's a woman out there for him. No, she's not going to look like a porn star. Yes, it's going to take some effort. But she's out there.
As for the men who claim "I've had many women, but they're all more trouble than they're worth so now I'm MGTOW" -- a man who has had moderate success with attractive women does not become MGOTW or black pilled. It doesn't happen.
"Lord, grant me the serenity to accept the things I cannot change,
the courage to change the things I can,
and the wisdom to know the difference."