Sorry! The advance is nothing more than the smallest price the publisher had to pay to obtain whatever rights they secured. The SMALLEST! Author, your publisher is trying to make money. Less exposure means a bigger upside. I don't care if you got $25K or $2.5M. Granted, the publisher has expectations based on where they believe the market will be in 9, 12, 18 - 36 months, how many units will sell and what other opportunities to monetize the content may emerge.
But the bottom line is that its a guess. There are some pretty good guessers out there, but we know most of these bets don't pan out.
Publishers are opportunistic but can't and won't "try harder" or "do more" based on the advance they paid. I love publishers! They do an awesome job of identifying great content. They do amazing work shaping the ideas. They are brilliant at producing a beautiful object to house, transport and represent your efforts. But they can't make anybody buy it. Only the author can excite people and motivate them to affiliate and buy the book. Only the author can turn fans into advocates who will spread the word.
Your advance is your advance. It's got nothing to do with selling books.