The Use of Reclaimed Slurs -- Why do we do it?

I have a legitimate question.

Why do marginalized groups insist on using words that are typically used as slurs to insult them?

Example: Black people call each other "nigga," gay men call each other "faggot," etc.

My perspective is that if it's a word rooted in hatred, it probably shouldn't be used at all, so as not to encourage hateful people to use it.