I went to a top liberal arts college, and majored in physics for most of my time there. Within the physics major, every single student was either 1.) An immigrant 2.) The child of an immigrant or 3.) Jewish. It was similar - though a little less pronounced - in the CS and math majors. Most of my friends there were from comfortable middle-class American backgrounds, and most of them majored in English, music, history, or psychology. Many of them are struggling financially or still dependent upon financial support from parents, 12 years after graduation.

The American educational system is such that you can largely make your own choices from college onwards (and to a limited degree, in high school too). This is a great strength of America, but it also means that sometimes people make choices that don't work out for them. The native-born citizens I know that invested heavily in learning math & computers when they were teenagers are doing great, even if they came from dirt-poor backgrounds. The ones I know who figured there would always be a job waiting for them, even if they came from very comfortable upper-middle-class backgrounds, are barely scraping by.