All the comments here mentioning the neoconservative desire for regime change in Iraq predating 9/11 seem to imply that it was an obscure thing that people weren't very aware of at the time.

But that isn't true at all. It was broadly understood and frequently discussed. It's just that people were so generally scared, pissed off, and ready for vengeance against whoever, that nobody cared. (Not literally nobody, but I think I recall that the war had like 70% or 80% support, with strong majorities in both major parties.)

This is why I started out my adulthood libertarian-curious, because both parties and huge majorities of voters seemed insanely interventionist to me. But things have reordered a huge amount since then. (Basically everyone came around to my view of the war, in hindsight.)