In the comments for The Cognitive Science of Rationality, Spurlock said

The beginning of this post (the list of concrete, powerful, real/realistic, and avoidable cases of irrationality in action), is probably the best introduction to x-rationality I've read yet. I can easily imagine it hooking lots of potential readers that our previous attempts at introduction (our home page, the "welcome to LW" posts, etc) wouldn't.

In fact, I'd nominate some version of that text as our new home page text, perhaps just changing out the last couple sentences to something that encompasses more of LW in general (rather than cogsci specifically). I mean this as a serious actionable suggestion.

There are couple problems with using the specific anecdotes from the post:

It would make the beginning of the post seem boring for anyone who had read the homepage.
There has been discussion on LW that the sunk cost fallacy may not be much of a fallacy in practice, and commenters on the post were also skeptical of the rare disease example.

But the idea of starting our website off with concrete examples, the way Eliezer recently recommended starting off essays, seems like a good one.

So what are some quick, concrete, compelling stories about how irrationality sucks/rationality rocks that we could put on the homepage? Bonus points if the story is straight from a study, or is a true story that happened to you or someone you know.