It doesn't promote white supremacy. It was created for two reasons
1. remind whites not to feel guilty for being white (depending on who you ask this is white supremacy) 2. to show how anti-white racism has been normalized (to some degree), by the inevitable over-the-top reactions to something inoffensive and anti-racist
And then dudes started associating the slogan with Pepe and put it on business cards that also have links to white supremacist websites. If a slogan I was a fan of was inexorably linked to racism, I'd find out the reasons why and adjust my usage accordingly. But you do you.
