Opportunities that require big risks is also another factor. My academic acquaintances abroad may be doing well financially and travel-wise, but they all have to live their foreign bosses' ambitions despite being very bright people. It's far easier to take crazier entrepreneurial risks with the safety nets in one's own home-country.
Entrepreneurship sure may be difficult as a whole. However, some difficulties are not really necessary. For me, it's a matter of seeing the end goal and removing as much obstacles as possible to get there faster (optimizing for time). I see the need to have a proper job or chase funding as additional obstacles if you are abroad.
