One, I myself do not think much of the idea that creativity necessarily attracts the mentally ill, or those prone to act on suicidal impulses, any more than any other field, but it remains current, despite Plath receding into history, that writers, especially poets, are more unstable than the general populace, and Woolf was never diagnosed with schizophrenia. The literature I have read suggests bipolar disorder, which is consistent with her writings for those who bother to study them.
Peter is also off in left field with his cancer thesis. Thompson crippled himself and was in a lot of pain, and that holds true for Hemingway as well, insofar as the biographical detail holds.