I think the implication is that people from third-world countries want what the US has so they're likely to take more risks to come to/stay in the US, whereas v

I think the implication is that people from third-world countries want what the US has so they're likely to take more risks to come to/stay in the US, whereas visitors from other western countries are less likely to stay because they have less to gain and more to lose if they're caught. It comes across as pretty racist the way they said it, but a charitable interpretation does make sense despite that.