[kelnos]

I think some are indeed going back.

Others have fallen prey to the sunk-cost fallacy ("I've been waiting for 10+ years; it'll feel like I waste if I give up now").

And still others value the ability to work in the US over other countries (though I would judge that value to have decreased in the past couple years).

Some will just still stop at nothing to eventually be able to hold a US passport, especially if they come from a country where their own passport is much less useful internationally.

And I imagine some have also settled down and had kids in the time they've been here, waiting, and don't want to uproot their family.