7. George Harrison, 1974 Tour - Cocaine
In late 1974, George Harrison launched a two-month American tour in support of his underwhelming LP Dark Horse. It was the first time any Beatle had toured America since the group's final outing in 1966 and tickets went fast, though the shows were quite lackluster. He did play Beatles songs like "Something," "While My Guitar Gently Weeps" and (surprisingly) the John Lennon-penned "In My Life," but he also gave Ravi Shankar a ton of stage time. The crowd didn't love the long sitar sets, but they also couldn't believe how awful Harrison sounded. He had a nasty case of laryngitis, and snorting mountains of cocaine didn't exactly make his voice any sweeter. By the end of the tour, his voice was absolutely shredded, and with the exception of a brief 1991 tour of Japan, he never went on the road again.