Why did Eminem dye his hair?

Because he felt like it, and he could. Not by necessity, he was his healthy natural blond by the time he bit the bullet at the ripe old age of 27. Fun fact: during Courtney's pregnancy with Frances Bean Cobain, she wanted to dye her hair but was advised not to so Kurt had his hair a deep, unnatural red until Frances was born. After the birth of their daughter, Courtney went to the red color and Kurt back to his natural hair. Of course he dyed his hair in multiple other occasions, but I think this one was the sweetest.