buttery81 . Trump's father, Frank, was not an immigrant. Frank's father, Donald's grandfather, was a German draft dodger (runs in the family), who made a moderate fortune running brothels, beer houses. Frank inherited that fortune and invested it in slum housing in Queens. He was a racist and a psychopath, who treated his tenants appallingly, and had a policy against letting to African Americans, which resulted in court action against him. Donald's mother, Mary senior, was a Scottish immigrant who worked briefly as a maid or similar before meeting Frank, and basically marrying into money. So neither of them were self made, as such. Much of the money they made through their slum housing empire actually came in the form of the tax payer's dollar - they exploited government grant after government grant for housing developments, and ploughed it into their own bank accounts rather than into the housing.
I think your assessment of Mary is unfair. She is the daughter of Frank Jr, who was the heir apparent. Frank was, by her account, handsome, charasmatic, kind and loved by his friends - everything Donald is not. Frank was not interested in the family business, he wanted to be a pilot, and was a very good one, one of the TWA elite. However, he could never get his father's or mother's approval for this. They basically abandoned Frank Jr and his wife and children in favour of grooming Donald as the new heir. The circumstances of Frank Jr's death from alcoholism, and the cruelty of Frank Sr and Mary Sr in their dealings with Mary and her siblings, is horrible.
Donald was a fair bit younger than Frank Jr, and a problem child. His mother had been hospitalised when he was 2, and his father was largely absent, so Mary's assessment is that he was largely an abandoned child. But following the fall from grace of Frank Jr, he was thrust into poll position as heir apparent (despite having 2 older and smarter sisters - misogynist Frank Sr was not going to pass the family business to them). Donald saw what happened to his brother and knew what he had to do to please his father. And thus, a monster was created.
Donald and the other siblings also allegedly cheated Mary and her brother out of her father, Frank Jr's, fair share of inheritance through dodgy tax returns and assessments of the worth of the family's holdings. This ended up in court proceedings, and it is from those public documents that a New York Times reporter contacted Mary for information about Donald's finances. Off the back of that contact, she then wrote her own memoir of her experience as a Trump.