Among other things, those documents can be Kompromat to keep his republicon lackeys in line.

He took them to sell later to foreign governments. It's all about greed and getting money from whatever he can.

He was asked, officially, for Months, to return them as they had no business being removed in the first place.
Oh, heeey, you don't suppose Nuclear Armament technical details would be worth any Money, do ya?

Any chance Trump might be wanting to sell the documents? He is not fond of reading and claimed he declassified the documents earlier himself. He would not have authority to do that in all situations. I've seen pics of some of these documents and they are redacted. Just a little strange. I also found out that Trump extremists have now threatened the life of the judge who issued the order.

Not strange at all. Such documents could be used for espionage purposes and he's just the guy who would leverage them for personal benefit.