You also have to consider the kind of business. You can't just carpet bomb all billionaires. He is in real estate which is probably the most anti-globalization business. His other businesses are mostly drip in ocean. Yeah he did take advantage of work visa etc but he had to, to stay competitive.
However, what is different about him is he called it out. Even though he was taking advantage of it, he said it is killing middle class and we need to close the borders and stop doing it.
On the other hand, let me give you example of a meeting where Bill Gates, Zukerberg, Bezos met Obama and DHS so that they can increase the length of working visa for students in USA. After that meeting OPT length was increased from 9 months to about 3 years with EO. Currently basically any student in USA can work here for 3 years freely on OPT. Good luck to Americans looking for a job. There were journalism majors at my ex-firm, working in marketing on OPT. Now that is called corporate greed. Bill Gates just decided to hit Americans economically so that he can kill mosquitoes in Africa and India and keep his number 1 status. Currently about 1 in 5 jobs in USA is being held by someone on work visa all the while, inflation adjusted wage growth is nil. U6 unemployment rate is close to 10%.