Most students who come here for a masters expects to work here for a while. With a student visa like an F-1 you can only work for a couple years after you graduate so they apply for a H1b via their employer. So what I mean is the H1b is incredibly difficult due to the lottery system and many people who actually deserve to be here basically have to pack up and leave after setting up their life here. This is a huge factor why international students are looking elsewhere