I'm SURE the underlying etiology of VM is actually a physical issue (imbalance of fluids in your ear). The condition gets its name from all the neurological issues that you get on top including migraines because the brain keeps freaking out from the mixed unexpected signals.
I suspect over time, the less you dampen the signals with meds, ie the more you expose the brain to symptoms, the more chance your brain has to compensate. However if the symptoms are too severe you head into migraine territory and there the brain will not compensate (IMHO migraine is the result of the adaption algorithm breaking down)
So basically it's a balancing act (ahem forgive the pun)
Meanwhile the underlying issue may improve and that adds another thing your brain has to deal with as the condition morphs.
Both of these things have happened to me I'm sure: I've part compensated and the condition itself has slightly improved. I'm off meds and no longer dizzy. Left with various symptoms though including mild imbalance most days. (but it's a huge improvement)