2. Ja Rule
In the early 2000s, you couldn't go anywhere without hearing Ja Rule sing-rapping. The rapper born Jeffery Atkins, who at one time was spitting alongside Jay-Z and DMX, shifted lanes and just-about single-handledly took hip-hop pop, thanks to his collaborations with Ashanti, Jennifer Lopez, and Christina Milian. But it honestly wasn't the lightweight fare that took its toll on Ja, it was the emergence of his real-life enemy, 50 Cent.
50 emerged like a buzz saw in 2003, with two goals: to become the biggest artist in the world, and to destroy Ja Rule, and not necessarily in that order. Ja, who 50 blamed partly for the shooting that almost killed him, went from karaoke favorite to perpetually mocked, and never recovered artistically. He's currently serving jail time for tax evasion.