This is completely false. Debt can absolutely be sold for whatever it is worth. In this case, the Jones' debt owned by the Sandy Hook families is fairly valuab

This is completely false. Debt can absolutely be sold for whatever it is worth. In this case, the Jones' debt owned by the Sandy Hook families is fairly valuable to Jones' other debtors because it means they get a bigger slice of the bankruptcy estate. Thus the Sandy Hook families can offer enough of their Jones' debt in the sale to make it more valuable. (Edit: more complicated than how I explained it because both sets of debtors include Sandy Hook families) This isn't any more "imaginary" than money itself.