This is a two-part conversation. Immigrants of two classes. First are those trying to legally enter with skills or wealth to bring into the country. Second are those entering illegally with little skills or education.
It is true that immigrants coming legally have to work with a broken and prohibitive immigration system. It is true that most of them have an entrepreneurial desire often denied to them in their home countries. I also believe foreigners are more likely to start businesses rather than relying on the "new" American idea of getting an good education to get a job. We have vilified risk-taking entrepeneurialship for the safety of working for someone else.