I don't get the point of your comment. Whiteness being a made up construct doesn't mean you can't talk about white people as a general entity, especially when that construct plays a huge role in society. And ethnicities are just as much social constructs as race

I don't agree with OP, I feel like they're being edgy just for the sake of being edgy, but even though race is technically bullshit that doesn't mean we get to dismiss the fact being white actually matters and means something, changes the way you're treated in society, etc.