The last paragraph of A Modest Proposal is the cherry on top of the satire. The narrator reaffirms that he is a loyal Irishman only looking out for the good of his country. Once again, folks, this is not an outsider proposing to sacrifice Irish babies as a food source. Nope, it's a guy who is only motivated by the dire plight of his native country, as well as the prospect of making rich people happy.
It gets better. If you think the narrator is trying out a get-rich-quick scheme, that's not the case at all. Swift's final satiric jab is that the narrator really does believe that his plan will benefit the nation. He can't even sell his own kids, since they're too old to get much money (35).
Remember, Swift has already run through a list of possible solutions that he actually proposed in earlier essays. At this point, he decides to go whole-hog with the satire to drive his point home.