Do you dye your hair - or change the color in any way?
Not at all, but I see a lot of people that do especially on my college campus.
The main reasons are cosmetic - to cover gray or to change to a more fashionable color - or even to correct bleaching by the sun
Most of the ones that I have seen are the girls that really like to dye their hair blue or red.
At home coloring has reached 1.9 billion and is expected to rise in the US