just want a space for whites. It is that simple

If only the reality was so simple. Ethnic purity is beautiful. Discrimination, Segregation, these are not supremacy because once your THEM opponents are out of the picture, your basic US can live in peace while THEM do their own thing. If US has the arete, the virtue to thrive, one might hope and expect US to grow tall enough to overshadow THEM.

Have a look at my recent post Downside of Diversity, for a sociological study on what happens in societies with too many outsiders.