[WalterBright]

Because when you own an epithet, it loses all its power over you.

[gowld]

Or it internalizes the negativity into low self-esteem.

[vzidex]

If you used these words with their original, negative, meanings, sure.

But that's missing the point - words like "bitch", "queer", and the n-word are used to mean positive things in their respective communities.