While it is subjective to determine whether a musician has "wasted their talent," there have been several cases in the rock genre of musicians whose careers have been marred by various issues such as addiction, personal problems, and legal troubles.
One notable example is Jimi Hendrix, considered by many to be one of the greatest guitarists of all time. Hendrix's career was cut short due to his untimely death at the age of 27, but his impact on the rock genre and music as a whole cannot be overstated. Despite his relatively short career, Hendrix left a lasting legacy and continues to influence musicians to this day.
Another example is Janis Joplin, who was known for her powerful blues-inspired vocals and electrifying live performances. Despite her talent and success, Joplin struggled with drug addiction throughout her career, which ultimately contributed to her death at the age of 27.
In more recent times, Amy Winehouse is often cited as a musician who "wasted her talent." Winehouse was known for her soulful voice and unique style, but her personal struggles with drug and alcohol addiction led to her untimely death at the age of 27. Winehouse's death was a tragic loss for the music industry, as she was widely regarded as one of the most talented musicians of her generation.
It is important to note that while these musicians may have had personal struggles, they have all left a lasting impact on the music world and their contributions to the genre of rock will always be remembered. Additionally, it is unfair to label someone as having "wasted their talent" without considering the complex personal and societal factors that may have contributed to their struggles.