Foreign cash buyers do contribute to the local California economy in the form of property taxes based on inflated house values (house values inflated in part by their interest in California real estate), Mello, HOAs, etc., and the sales tax on the expensive stuff they buy. If you do the Trump and kick them all out, Irvine may have a hard time paying for its police, schools, etc. So you have to kind of take the good with the bad (birth tourism). As others have mentioned, those folks who are doing birth tourism may be the same folks buying these $1M properties in Irvine, so I doubt they're all that interested in California welfare benefits. But I could be wrong.