When you live with someone suffering from an acute mental illness such as borderline personality disorder (read: borderline psychotic) or malignant narcissism, your natural tendency is to adopt their worldview. To do anything else is to invite constant battles over interpretations of events.
The narcissist will tell you how awesome they are in 800 different ways every day even though they may be quite ordinary or below average at whatever is being discussed. If you disagree with the narcissist, you'd best be prepared for an all-day, violent argument. Disagreement threatens the world the mentally ill person has created for themselves. It's an existential threat to them, so fights over even trivial items can go nuclear very quickly.
Such arguments exhaust the sane person and so you avoid them. If you can't escape the relationship, you become slightly crazy yourself, interpreting things through a variant of the crazy person's eyes.
That's where we are right now in the US with gender and race.
Bruce Jenner (is about to) cut off his genitals. He's consuming massive amounts of female hormones, had plastic surgery and dresses up in women's clothing. He demands we call him a woman and we all have to obey because crazy people tell us we should. If we disagree with them, they'll escalate the dispute to nuclear levels immediately and spend the day screaming at us.
If Joe Smith in Scranton cut off his hand, consumed a pint of rum a day, had a prosthetic attached to his arm and dressed up in a pirate costume, when he demanded we call him Captain Hook and treat him like a real pirate, we'd send for a psychiatrist. That's because Joe wouldn't be focusing on sex and sex (and race) is the focal point of the crazy people in the country.
Without a pack of crazy people willing to scream at us, we'd treat Joe like we should treat Bruce Jenner. We'd be sad and sympathetic, but we wouldn't call him a woman. Joe Smith would not be doing the things pirates do just as Bruce Jenner can't do the things women do. Ergo, Joe is not a pirate and Bruce is not a woman. They're guys who cut off body parts, consumed lots of drugs and dressed in costume.
Now we've got Rachel Dolezal claiming to be black and the crazy people are supporting her. Rachel is less a black than Bruce Jenner is a female. Bruce is at least saturated in hormones. Both dress in costume and both are altering their physical appearance. Like Bruce, she's not black, she's just crazy.
Life with the mentally ill gradually becomes untenable. Your friends aren't willing to crawl into the hole of insanity you've dug for yourself, so they slip away. Real world decisions need to be made that conflict with your adopted insane world view. You either destroy your life trying to live with the mentally ill person or you eventually give up, get away from them and return to normalcy.
That's where Rachel and Bruce have placed us. People across the Internet are all tumbling to the same conclusions - if race and gender is something you self-identify and there are lots of benefits to being a black woman when it comes to college admission, government contracts and the like, you'd be a total rube not to self-identify as a black woman.
The obsession with race and gender was always crazy, but we went along with it because crazy people were going to scream at us if we didn't. We've now reached the point where we choose to either further ruin our lives or escape the lunatics.
In all seriousness, I'm not sure which way to bet.