Why do people try to change their skin pigmentation: bleaching and Tanning!

Bleaching is brought about by being hyper-conscious of how one's skin looks like. The more one gets obsessed with one's skin pigmentation in a negative manner the greater the chance that one might bleach. 

The statement 'Black is Beautiful' is part of an obsession with one's skin pigmentation. What's beautiful is not 'black' but the person uttering the statement. 'So and so is beautiful or X is beautiful.' 'Black' as applied to people is a social construction but X is not. X is a human being. Instead of glorifying a social construction meant to debase a human population, we should glorify Xs...human beings.

And remember, what is important is not that someone is bleaching, what is important is that someone is not comfortable with their skin pigmentation or how one's nose looks or how one's chest looks. This is all about self-esteem and it applies to all races.

People of European descent tan because they believe tanned skin is more beautiful than pale skin. Tanning can result in skin cancer. Others go through dangerous plastic surgeries or facelifts...
Any attempt to change one's natural looks is a function of low or questionable self-esteem no matter the race.