In answer to your question "what is wrong with holding the opinion that the White Race is superior..."
- it's not true
- because of this erroneous belief white people enslaved, kidnapped, raped, whipped, "bred", tortured, etc. black people
- after slavery was abolished this erroneous belief caused white people to lynch, firebomb the homes & churches, burn crosses, refuse to sell to, employ, educate, etc.black people and to institute a whole new set of Jim Crow laws that sought to return black people to financial and social bondage if they couldn't be returned to physical bondage
- even after the civil rights act of 1964 was enacted this erroneous belief of white supremacy prompted some whites to simply ignore these laws and continue their racist behaviors (have you seen the movie Hidden Figures?)
- last (at least for now) racism as opposed to "being a racist" is unlawful
Trump's statement about never apologizing to those whom you view as your "inferiors" is idiotic to say the least and very juvenile. But that's another topic for another day, maybe.
Keep in mind, the title of the thread is asking a question. Do not confuse that question with making a personal statement, or statement of fact.
Trump very strongly believes that one of the great sins is to apologize for anything. I can practically guarantee you no matter what he says or does, no matter how wrong or offensive or racist he maybe, he will never apologize or admit to a single error. And his base, especially racists, are energized that he never backs down no matter what, no matter the cost to others, no matter who suffers for it. Its one of his long standing rules of life, one that he never forgives if someone crosses that line.
Is trump a racist? Yes to a limited degree just like nearly everyone is. What he does is uses racism as political tool to get what he wants. He tapped into a voting block no candidate or party was willing to touch.