Transgenderism is false.
Claiming a male is a woman requires a redefinition of “woman.” The original definition, adult human female, excludes males by definition.
They fabricated a sex/gender distinction, saying that sex is biological, but gender is a "social construct," and reassigned female-designating terms ("woman," "girl," "lady," "sister," "daughter," "she") from biology to this new "social gender." This lets anyone "identifying" with that gender claim the whole cluster. They target these labels precisely because everyone pictures a female; they want to be female, they are not, so they demand the words.
If transgender grew in number enough that "woman" no longer reliably signaled sex, the public would drop it for "male" and "female." Transgenders would then abandon "woman" and chase "female" instead, inventing new distinctions like "biological" vs. "social female" to justify claiming it. "Social gender" is not valued for itself; it is pure mimicry of females, a rhetorical tool with no purpose beyond hijacking whatever word females currently use.
You can use this trick to claim to be “trans” anything by just redefining the words. One could claim there’s a difference between “biological age” and “social age.” and then redefine words like “baby” to refer to the “social age” instead. So a guy in a diaper could enter a nursery. This is not any more ridiculous than transgender. The only reason you might see it as a joke is that you haven’t been blasted with propaganda to normalize it as you have for transgenders.