Well, there's heavy survivorship bias in the linked article, which talks about 582 startups founded in the US that are worth $1 billion.
Meanwhile, another comment here noted that there are about 45 million immigrants currently residing in the US. Only a tiny number of those are founders of the aforementioned startups. The article says nothing about how immigrants are doing overall financially compared to native born US citizens.
Thomas Sowell (arch-conservative) wrote about this.
Germans who immigrated to Imperial Russia, Indians in South Africa, Chinese in Malaysia, Japanese in Brazil, etc. all do much better than “natives.”
When people spy opportunity elsewhere, and have the money to move, and snatch the opportunity- it turns out well.