Why weren’t more white U.S. Southerners abolitionists?

Not asking for moral defense of slavery— there is none— but asking what was going on with society, that kept slavery socially and politically popular among non-slave-holding whites in the antebellum South.

From what I’ve read, 75% of white Southerners did *not* own slaves, and yet they were so committed to defending the institution of slavery that there was a whole war about it.

What was behind that? If you’d asked an average poor white person why he wanted slavery to continue, what would he have said?