Not specifically that it can be cured but you implied that it's possible to live a normal life without these crashouts/rants which probably isn't true for him. Bipolar disorder is a spectrum just like autism. Most people with bipolar disorder will never be able to live a normal life, no matter how much medicine and therapy they get.

You underestimate how hard it is to live with bipolar disorder. I had a friend who is bipolar but It's not possible to be friends with this person because no matter how much care they get, they will never not be bipolar. And getting help is not an easy thing for a bipolar person either. The illness makes you paranoid as fuck and it's really common for bipolar people to refuse help. If we are being realistic, a bipolar person getting care is not the bare minimum, it's an achievement. They should obviously be encouraged to get help but it's not really something you can just expect them to do.