Why were impeccable artists drunks/drug addicts?

Why do you think that a vast majority of impeccable artists were drunks/drug addicts?
Why do you think that a vast majority of impeccable artists were drunks/drug addicts?

This article in NYT (bit.ly/nyt-artist-addicts) provides one explanation: the relation between genius art and addiction in the past can be attributed to a belief that addiction/mental illness and artistic genius went hand in hand. As society has moved away from this belief, the stereotype has become less common and great artists have become less likely to embrace this lifestyle.