You're ignoring the asymmetry with security. The attacker just needs one exploit chain, whereas the defender needs to block every avenue. Open access to models with no guardrails greatly benefits the attackers more than the defenders.

Imagine what a god-level hacking AI could do. It could find a full 0-click to root exploit chain in iOS. Attacker unleashes a worm that infects a phone, instructs that phone to send the same attack to all of its contacts, and then physically destroy the phone by turning off all thermal throttling. Might even be possible to make it catch fire.

Or find a remote exploit in Tesla cars and make their autopilot go on murdering rampages. (that one is from a movie)