The processing fee is stated to be nonrefundable, and the gift is a gift: it is given to the U.S. government, it earns nothing, and it is not repaid. There is no financial return attached to any part of this programme because nothing about it is an investment.
Money that goes and does not come back
This is the point on which people most need a plain answer, and the plain answer is that the money is gone. The processing fee is nonrefundable by its own terms, which means it is spent whether or not vetting is passed and whether or not the application succeeds. The gift is not a purchase, a deposit or a placement.
It transfers to the U.S. government, it produces no income, no share and no repayment, and there is nothing to sell later. Hypothetical example: an applicant near Saint-Joachim-de-Shefford asks what the money will be worth in ten years, having been told by an acquaintance that it works like a bond.
It does not work like a bond, and the acquaintance has confused it with something else. Anyone describing a yield, a payout or a buyback is describing a product that is not this one, and that description is itself a warning sign. The honest way to plan is to treat both amounts as permanently spent from the moment they leave the account.