Past advance sales of large blocks of miles to credit card partners have on balance probably been good for members, borrowing against the program may not be although it’s far from a foregone conclusion.
You’d expect lenders to want a strong program to secure future member interest and an ongoing revenue stream yet in practice that’s not how things usually work out. Still, while Delta has a strong elite program, there’s really not much left to devalue on the earn-and-burn side.