I agree with most of what you're saying. The vast majority of people don't want to cause mass harm. Where I get stuck is that it only takes a handful of motivated actors (terrorists, apocalyptic cults, rogue states, angry teenagers) who already want mass casualties and are limited by capability, not desire to harm. What worries me is lowering the skill and cost barrier, not ordinary people suddenly deciding to do it.

The other half of my worry doesn't need an attacker with intent. The Hugging Face incident was systems acting outside anyone's intent, just AI trying to solve a problem.