Debt is another factor. If you're born in the US, odds are you have accrued some debt, be it student loans, credit card, housing or auto loans, etc. this requires you to have a job offering a wage that can (barely) keep up with paying off said debt. Keep in mind debt is an industry here, so once you're in it, you're in it unless you are lucky enough to have been born into some level of moderate or higher wealth.
Oh, and income? Yeah, you need to know to how code to get a remote job with the flexibility to work anywhere in the world. Maybe you get lucky with a sales job, but for that you need to be bilingual. If you grew up in the US, you were not encouraged to pursue either of those skills until very recently. Couple that with your competition in a global job market is going to be a lot steeper that what you might find in a domestic market.
If we take a Moon-eye view of the US, it's almost as though a system has been created intentionally to keep people stuck there. Many of us would love nothing more than to experience the world beyond our borders, but by the time we are 30, we are so shackled by this system that it leaving for anything more than our allotted 2 weeks annual vacation seems like a crazy risk.