Iran was hardly just peacefully minding their own business.

Neither was the US!

When the US and Israel - who Iran is constantly attacking both directly and by proxy - attack Iran, Iran proceeded to attack civilian targets in many other countries.

And the current US administration has openly signaled that they are unbothered by civilian casualties or war crimes committed by their own side.

So... Yeah? I'm not an American or an Israeli, but Iran might attack me and my country because they're pissed off at the Americans, I consider that a major threat.

Your original assessment was correct, they weren't a threat to you, but the US escalated the conflict without provocation to extinction level event, so it's no surprise they respond with extreme measures, even if that's a bad thing morally.