He lost the battle with his demon.
That makes me sad.
Contrary to others on this thread, this does surprise me. For all of his reputation for weirdness, drugs never seemed to be a part of it. I didn't know him personally, but this seems more of a case of accidental addiction to pain medication rather than being a druggie for the thrill of it. Prince's lyrics were always anti drug.
He did have physical problems with his hips after a long career dancing on stage. By 2009, seven years ago, he was actually singing about needing a hip replacement. That is plenty of time to become addicted to painkillers.