Comedian Neil Hamburger once joked, "Why did Britney Spears get so addicted to cocaine? Because Kevin Fed-Her-Lines!" This is, perhaps, unfair, but it's hard to deny that Spears becoming Mrs. Kevin Federline coincided with her sad descent into drug addiction, mental illness and a near total career flame-out.

It once seemed impossible or at least extremely unlikely. When Spears burst onto MTV's Total Request Live in fall 1998, her appeal was obvious. She may not have been possessed of Mariah Carey's pipes but—like Madonna before her—worked well with what she had. More importantly, she was mesmerizingly charismatic; a formidable presence on camera. In short, she was a product, and as such seemed unlikely to start donning trucker hats and wife-beaters and marrying every mistake in sight.

A decade later, all that and worse had happened. In January 2008, recently divorced from Federline and fresh off of publicly shaving her head and bashing a paparazzi's car with an umbrella, she became uncooperative during a routine turnover of her sons to Federline's representatives and ended up hospitalized when police were summoned and concluded she was on drugs. The following day, she lost custody of her children entirely and was committed to a psychiatric ward. A February 2008 Rolling Stone cover story on Spears' decline lamented, "Even Michael Jackson never deteriorated to the point where he was strapped to a gurney, his madness chronicled by news choppers' spotlights."

In the five years since, Spears has mounted an impressive comeback, but this has meant her father placing her finances in conservator-ship and retaining this control long after the singer began behaving herself. As for her art; her music is still fun but she's now lost in a sea of imitators. Her once assured rule over pop music has long since been abdicated to the likes of Lady Gaga, Miley Cyrus and Katy Perry.