Imagine the same random bubbling up of thought, but instead of appearing as a compulsion, it appears as a really clever idea that will change the world (e.g. a higher-level goal that will generate its own sub-goals that you then seek to achieve, etc.) Thinking about, and planning on how to execute, the idea suddenly produces a dopamine response (a feeling of passionate motivation), in the same way that e.g. planning how to get to a casino when you're addicted to gambling produces a dopamine response.

At some point, the artificial pin of the idea as "really clever" and "world-changing" goes away—but you might not even notice, if you're way down in the subgoal stack trying to solve a small part of (what you see as) the problem.

You have to actually pop back up and re-evaluate whether you still have confidence that the thing you think is a good idea, still is, before you notice that the idea was never that good in the first place and what were you even thinking.