It answers the question to the extent that, if you're looking for the entire fare, it doesn't come from anywhere. The explanation in the second post explains where a penny or two per mile come from. The rest of it was never really there to begin with. It's the airline's "funny money" price. You could say that the airline pays the difference by accepting much less than that for the seat, but they accept much less than that for just about every seat they sell up front.

Perhaps you couldn't buy the ticket for less, but most of the people who buy them - including partners who buy them with your miles - do. If an airline thinks someone might show up with a credit card to pay for a seat, it won't release that seat for an award. Yield management systems won't release award seats unless they figure that the probability of selling them is under 10 percent, sometimes way under.

Finally, there's no such word as "anyways" in English.