The symptoms of OCD are involuntary only in a relative sense. Relative to a determination to remain within his defensive bubble of non-engagement, there is nothing much that the obsessive-compulsive can do about those symptoms. He can engage in a bit of ‘cognitive-behavioral therapy’, but the effects of such therapy will be shallow and short-lived, absent a determination on the obsessive-compulsive’s part to grow and change himself in a way that makes his OCD irrelevant. On the other, if he does choose to leave his defensive bubble and re-engage the world, then, indeed, his OCD will become irrelevant. So relative to a determination on his part to re-engage the world, the symptoms of OCD are voluntary.
So ultimately OCD is indeed voluntary, and if one sees it for the voluntary condition that it ultimate is, then the prognosis is 100% positive. But if one sees it as a garden-variety pathology, then the prognosis is negative.