Yes giving people with fewer resources an option to pay with their attention is a morally good thing for society, actually.

Even better, morally, to give the product to them without harvesting their attention or personal data

No, that's charity, which while morally great is not sustainable at scale and in the long run.

Considering how prominent gambling and gambling advertising is, aren't we creating more poverty and keeping people poor through ads? Advertising seems like it's a net drain on the poor through encouraging consumption people can't afford and pushing a variety of vices.

Edit: "Sorry your husband lost the money you were saving for a house on stake.com, but here's your free Google search."

Disagree; these users are already subsidized by those who click ads and buy things.