1. They are paid to include promotion material/ads with their item (even though it violates MM rules)
2. They have a special Media Mail presort rate we smaller sellers do not have access to
3. The "charity" megasellers get their inventory for free, non-charity megasellers get their books/media so cheap they are practically free
4. The "charity" megasellers often employ sub-minimum wage workers, or are even paid by the government to employ them (they actually make money employing people, not actually selling items)
5. The megasellers do not take actual photos of their items (use tiny stock photos, or have no photos at all even though it is against eBay rules), have blank (or worthless) descriptions, do not examine, grade and note defects on the items they sell. They can sell them cheap because they put virtually no work into their listings.
6. Because they don't examine their items, their quality control is poor but because they are so big can afford to have a high return rate (and high negative feedback) that small sellers cannot afford.
7. They usually use cheap, substandard packaging (they can afford to eat the cost of returns for damaged items).
There are rare/collectible books and CDs and other media that are worth good money and absolutely worth selling. Unfortunately, books and media are now an "advanced category" that requires experience and knowledge to be successful with. It is definitely not a category for beginner sellers.
