The real goal may be to get people to believe four equals five

One of the proofs that someone has completely submitted to...something...is when the person enthusiastically agrees that one plus one equals three.  Or that freedom is slavery, whatever.

George Orwell understood this perfectly:  In his classic, 1984, the men torturing the protagonist held up four fingers and demanded that Winston Smith tell them he saw five.  Only by agreeing to the lie would the torture stop.

You've never encountered this kind of system before, so you don't believe this really happens.  How could you?  It's outside the experience of civilized society (almost).  You can't believe any society, any human system, could do something like that.

But read the writings of Solzhenitzen.  Do you claim he was lying about the gulag, friend?  Or is this another situation where "I never heard about it, so it didn't happen"? 
 Latest example:  It may well be that a handful of idiot liberals who support the transsexual agenda really, truly do believe that men have menstrual periods.  It's insane, of course, but heaven knows there's a ton of than going around.

But I'm pretty confident the average liberal didn't come up with that insanity on his or her own.  Rather, someone up the food chain told 'em that was true.  And also told 'em that sensitive, caring, loving liberals would support this idea.  And finally, that only the most sophisticated people could recognize this as true. So if you don't agree that it's true, it means....

And astonishingly, as if on cue, a few dozen of the most-sophisticated liberal bureaucrats popped right up and supported this insanity.

Whereupon another hundred or so likely thought "I don't want my peers to think I'm primitive, unsophisticated...deplorable, so....  Whereupon the insanity that men have periods became official policy at universities and public school systems.

You say you can't believe anyone could be that crazy?   To demonstrate its “commitment to inclusivity,” Washington State University has begun stocking men’s restrooms with menstrual pads.

Read it again:  Not "unisex restrooms."  *Mens'* restrooms.  The crazy pencil-necks running the Directorate of Diversity and Inclusionary Policies" have really, truly done that.

Of course if your goal is to brainwash people into believing absurd bullshit it's best to start 'em very young, before they have even a basic understanding of reality.  For example, in Britain public school systems are teaching children as young as 8 that “all genders” can have periods.

The teacher guidance, from the City Council, states: ‘Trans boys and men and non-binary people may have periods.’ It says language about menstruation must be "inclusive of all genders."

If you accept that as reasonable, it makes perfect sense that the U.K's government-run healthcare system invites men who have declared that they're women to be tested for cervical cancer — even though they don't have a cervix.

Perfect.  Sense.