> Many PhDs in America expect you to be self-supporting, so you have to take up a loan.
This is not true in America, at least not in the sciences. I've never heard of a reputable computer science PhD program in the United States that didn't wave tuition and provide a stipend for its students. Additionally, all of the of the other PhD students I've met in the sciences have a stipend from their program. Sometimes those stipends have strings attached, like teaching requirements.
Just last year a professor and two Chinese nationals at Harvard were indicted for something similar: https://www.justice.gov/opa/pr/harvard-university-professor-...