We have quite a lot of data on who does or does not get matched to a residency position. For example, in 2016, foreign international medical graduates (IMGs) had a match rate of 51%, compared to rates of 89% for seniors+graduates of US medical schools and 54% for US IMGs. [Main Match Results and Data 2016](http://www.nrmp.org/wp-content/uploads/2016/04/Main-Match-Results-and-Data-2016.pdf)
51% is a coin toss. It’s not ideal, but for most students that 51% shot is preferable over spending half a million dollars on a US college and medical education - money that most aspiring foreign doctors simply don’t have.
There’s another more detailed publication that drills into how IMGs that successfully matched into their preferred specialty differ from other IMGs, broken down by citizenship status and preferred specialty: [Charting Outcomes for International Medical Graduates 2016](http://www.nrmp.org/wp-content/uploads/2016/09/Charting-Outcomes-IMGs-2016.pdf)