"The Doctor Isn't In" succinctly describes Psychiatry's big problem: https://news.ycombinator.com/item?id=10315705
You're right, medication does not necessarily ever stop. But it also never stops for heart disease, diabetes, arthritis, HIV, ...
Some conditions can be cured, some conditions can be treated, some conditions require continual changes and adjustments to medications.
For example, some people with mental illness can take drugs for a finite amount of time, and eventually come off them and never have to return to them. Similarly some people who have asthma can eventually come off an inhaler and never need it again.
Even in those cases, some people in certain stressful situations can still end up needing to go back to the medication (e.g anti-depressant/inhaler) years/decades later.
Some people have to stay on their medication forever, either asthmatics and their inhaler, or people with mental illness and their specific meds.
For some people different meds are needed, but that applies to a huge array of drugs -- some people have to use specific brands of inhaler, even specific types of insulin, neurological drugs are no different.
And if we start looking at the merry-go-round of changing drug regimes, there are other diseases with similar cases, most obviously HIV, where the treatments have to be continually monitored and changed for each individual, and many have to be taken at fixed times.
Mental illness is not a unique disease, the challenges of treatment are not dramatically different from all other diseases.
It's just a disease, and like any other disease, living with it takes effort.
You could say the same thing about a lot of neurological disorders. Or things like Type 1 Diabetes, come to that.