Of these, half of the founders came to the US for university[1] (25% of all unicorns). That would be a pretty wealthy or non-representative group to begin with, since international tuition is very expensive, no? As a whole, immigrants have higher poverty rates in the US than native-born residents[2], which is also an interesting data point to juxtapose with this.

[1] https://www.forbes.com/sites/stuartanderson/2022/07/26/most-...

[2] https://www.irp.wisc.edu/publications/focus/pdfs/foc262e.pdf