That's not how mental illness works. I am not diagnosing Kanye, but look up the progression of bipolar disorder. It is truly terrifying and heartbreaking.
Whatever is going on in this individual case, Bipolar disorder is terrible. It can look like someone is "fine" for a long time, but then they aren't fine and people look for what changed, and what changed is progression of the disease.
It's really hard to talk about without adding stigmatization.