There’s a slight irony in your comment about his performance reviews - how did that get out? Apparently leaking isn’t always a problem :)
Your talking about legality is a straw-man anyway: the point is mass surveillance being highly unethical. Not even the law reflecting that fact makes the reality of it only worse.
Nice comment under an article that specifically calls out state gaslighting (false claims that portray the whistleblower as a bad/immature/insane person, or discredit them in another way).
Besides, swiping only the most telling and highligy classified documents would've aroused suspicion. He might have been including some line noise to distract a system looking for patterns. Also, including unrelated but genuine documents would make his leak easier to verify because it proves he has access to the source.
Say you exfiltrate not enough and are fired. You're shit out of luck, and there is no way to infiltrate someone else to your position to get the rest out.
I doubt you can honestly see his actions as reckless or revengeful.
For the same reason, I don't believe Assange was a rapist.