You can't contagion your way into severe gender dysphoria. It tends to be stable over time and intransigent to everything. This has been reasonably well studied.

But you might be able to contagion your way into interpreting mild anxiety over puberty or social roles as "being trans". It's worth keeping an eye on.

The key, however, is not to compromise the care of the former group out of worries that the second group exists.

What you're saying is hard to distinguish from advocating exactly that. "Vanity is not worth permanent medical complications" isn't a statement applicable to the first group. It's not vanity. It may or may not be a somewhat-tolerable situation, but outside of other serious situations like body dysmorphic disorder (which is like "vanity" in desire, but not at all like "vanity" in impact on the person who has it), the comparison is not apt.

One has to be very careful to avoid confusing a contagion-like phenomenon (and contagions do happen--take goth hairstyles for a mild one, or suicide for a dire one; one can't just dismiss the idea outright) for there being a range of severity in gender dysphoria. "You are not constantly screaming in agony, therefore you don't need painkillers" is not a humane outlook.