If I had to guess, whatever documents he stole that are so top secret that describing them is top secret, it was insurance for his re-election. Like a list of all of the CIA's agents and informants in the Kremlin, and he'd give it to Putin in exchange for Russia hacking the election again, and this time probably actually hacking the voting machines to literally change the voter counts. Because he doesn't actually need to win, he just needs to create enough confusion that the GOP declare him the winner and the military backs them.
Which given how the Pentagon has been erasing their own records of Jan 6th, I don't know why people think they wouldn't back him.