The money this siphon brings in is benefiting not just tech workers and tech shareholders. When the money is spent it turns the wheels of our economy, which leads to prosperity for all Americans, not just the 8% or so that work in tech.
The tech industry vacuums up money from foreign countries and pumps it into the economy of our country. The beneficiaries include all Americans, including those who work in restaurants, retail, healthcare, insurance, education, housing, transportation, entertainment and so on.
Limiting tech industry to whoever companies can hire locally will hurt its global competitiveness. Such a move will not just hurt the few would-be tech immigrants that are prevented from immigrating, but American prosperity in general.