There is lots of discourse about FND on this thread. The thing with FND is, there is a psychiatric component.
There is no obvious disease affecting the body, yet you get symptoms affecting your functioning. The research suggests a background of stress/ACES etc are significantly more common in people who have FND.
CBT is a suggested treatment.
I work in mental health services. You would be surprised just what physical symptoms mental health can produce. Psychosomatic symptoms are a thing. That does not mean what you are experiencing is not real, but there is still a psychological component. The same goes for things like fibromyalgia. Things like non-epileptic seizures are a thing within mental health!
It is naiive to think these illnesses are solely physical because the are not.
Also, from a psychological perspective, people absolutely do get stuck in learned helplessness and the sick role.
I cannot comment on random tik tok uses etc, but these are genuine things that happen. Believe it or not, there are people who unconsciously do not want their health to improve because it serves a function psychologically.
That being said, these people are still absolutely deserving of care and support.