It's the latest craze that's morphed beyond political correctness to indisputable orthodoxy. Dissent is not permitted. If you ask questions, based upon common sense, biology, a few thousand years of human history, or even religious conviction, you're a bigot, a hater.
Proponents (especially activists) of gender fluidity believe biology is not destiny. In their view, biological sex is mutable, something "assigned" at birth. One's "real sex" is determined by one's feelings about gender, conveniently presented as an ever-lengthening spectrum of choices (some social media are offering 112 gender choices).
For proponents or activists, (most people struggling with gender dysphoria are not activists¹) there is a clear set or steps a person should pursue once they self-identify with a gender that does not align with their biological sex.