Why would that affect us? Why would less diversity mean anything? You can say this but would it actually affect anything?
You also want diversity because you want the best people for a given situation, and the odds it's actually a bunch of rich white kids that are the best at being doctors and lawyers and whatnot is basically zero.
But I agree with my sibling commenter; ChatGPT will give you the best form of this argument, better than anything I can write.
I won't really be able to explain all of this here, but I do need you to understand that what you're arguing for is to allow more people to be oppressed because of their skin tone. I know that's not what you want, that's not what anyone wants.