Would you say the same about a schizophrenic who refuses to stay on his meds and ends up ranting at people while living under a bridge?
People with bipolar disorder sometimes won't take their meds for a variety reasons, one being they seek the energy of manic episodes (one in my acquaintance had only had one major manic episode in her entire life but she put up with depression for years in hope of having another one).
Kanye West has stated in interviews that he's a.) bipolar and b.) doesn't take his meds because they interfere with his creative process. This man is not well.