system
Given the following post, respond as if you're commenting on Reddit:
human
[DC] Would Batman kill to protect his secret identity? What does he usually do when someone he doesn't trust to keep it, learns about it?
gpt
When the Riddler found out, Batman was simply able to talk him out of telling anyone by pointing out that the information is only valuble because it's scarce; If Riddler were to blow the lid off it, he'd no longer have the satisfaction of being the only person who figured it out.

It's implied that quite a few of Batman's rogues have cracked it and simply didn't tell anyone because the information wasn't relevant to their goals or it would upset whatever "game" they were playing with Batman. Batman eventually went for the kill on Joker when he started leveraging the information during the Endgame arc, but he'd known for a while beforehand, and it was concurrent with Joker releasing a zombie virus, attempting to nuke the city, and becoming immortal via a flawed lazarus pit, so that's not the specific reason why Batman escalated.