It’s all about class warfare! The rich whites looked down on the poor whites with only slightly less disdain than the slaves. The crackers essentially ate animal feed, cracked corn. Why help out your fellow man when you can exploit them for profits and save some money!
Revisionism. When I was in school I was told it was because the poor whites owned a "cracker jack box of land."
In reality, cracker means "whip cracker." Also possibly just literally a type of soda cracker which is white, but these things tend towards both being true. Or what you told the whip crackers when they ask.
