I think TPM Reader DP captures a key element of the Trump documents story …
I think that ‘selling classified materials’ is too narrow an understanding of what Trump does or could do. I suspect his world is characterized by all kinds of exchange relations and forms of reciprocity. Like many people, he builds relations by giving supposed gifts. Recipients know to give back in certain ways if they want to maintain or shape the relationship. And others advance gifts to him on the good chance of reciprocity. This is not specific to Trump. It is how business people, politicians and others make their way, doing what they do. No doubt many folks hope to get to money deals when the chance arises, but at this level of gifting, all kinds of things can be leveraged. Why else to join an expensive golf club?
I suspect he thought he had a big collection of juicy stuff that he could exchange not directly for cash, but to build relations of reciprocity with powerful people that would lead to him getting what he wanted or needed. He could hurt someone via the top secret information and offer this as a gift to someone else. He could help someone directly with secret information. In a sense, the US government already does this reciprocal back-scratching via all that makes up the project called US national security. But the exchange relations are institutionally established, monitored, and enforced. Trump wanted to grab some of this good stuff and go solo, cutting his own deals for his own gains.