The reason for this "fad" is straightforward — there are a lot of middle-aged humans who are undiagnosed because ADHD was effectively "not a thing" when GenX were kids.
> …demanding diagnosis and prescriptions.
Great! People of all ages should advocate for themselves and pursue health care that might improve their quality of life.
Or to the extent that it was, they only knew of it through narrow or outright inaccurate stereotypes. It's become a somewhat common story over the past few years in online ADHD communities for Gen X and older Millennial parents to get their kid diagnosed and have a "wait, that's not normal?" reaction to the explanation of how the condition actually tends to manifest.
One approach is to work with a medical team over time to document symptoms and impact on your life, experiment and document attempted treatment alternatives, escalate to appropriate specialists as necessary, etc.
Another approach is to spend a weekend reading blog posts, forums and chatting with your bros, then convincing yourself of a particular syndrome/disease you must have, urgently scheduling an appointment with a brand new medical practitioner, refusing to discuss your medical history or symptoms since you already know everything, demanding a particular and specific treatment, refusing to discuss alternatives and then becoming hostile and aggressive when that practitioner doesn't immediately write you a prescription for the particular medication or expensive test that you have already decided that you need.
That second approach is a caricature that unfortunately approaches a modern reality, and it isn't what I'd term as "Great!" for anyone involved. The first approach is equally horrible since our system is so back-logged that the amount of time and personal effort between starting the process and receiving the help you need is onerous.
Note that this applies equally well to gastro-intestinal distress as it does to ADHD or any other chronic condition.
There are plenty of "pill mills" and "scrip doctors", and plenty of patients who will abuse that gray-market system. That is not what I'm referring to when I talk about self-advocacy by people who need actual, legitimate help.
Ritalin is a stimulant that tricks the brain into believing it needs to perform and focus.
Saying
"I have ADHD, so I need my Ritalin to be normal"
is equivalent to saying
"I'm depressed and anxious, so I need my cocaine to feel normal"
It probably does help! If you are stuck in a rut, external tools can break you out and show you what the other side is like. But using drugs is basically lying to your brain.