"If we're not going to educate our kids, bring in other people who want to become Americans," said Greenspan, in arguing for an increase of H-1B workers.
H-1B is not a path to citizenship, apparently by design. Green card holders can say "Screw you, I quit" without deportation, which is not what companies want when they reach for H-1B's.
In the context of income inequality, Greenspan put the H-1B program in his light: If the program were expanded, income wouldn't necessarily go down much, "but I bet you they would go down enough to really make an impact, because income inequality is a relative concept.
H-1B's are competing for the bottom. Executives don't bring in indentured servants to be their own replacement, nor are meaningful numbers being placed into "rock star" slots (rock stars can command perks like actual green card status anyway). H-1B's only drive down the wages of the bottom, not the top, exacerbating wealth disparity.