GDP (or equivalent) gains. Ricardo only says big aggregate number go up (with a bunch of caveats). Not for whom within that aggregate. It can (hypothetically)

GDP (or equivalent) gains. Ricardo only says big aggregate number go up (with a bunch of caveats). Not for whom within that aggregate. It can (hypothetically) be one person seeing huge gains while every single other person loses a little bit. Or, pick any more-plausible scenario that sees a very-few benefitting greatly while the net for the rest of the population is somewhat negative.