Imagine being the one who figures it out
Facebook spotted the hole after it noted a suspicious "spike" in user activity on Tuesday. The attack was "fairly large scale," it admitted, and when it investigated the cause, it discovered hackers were using the site's API to automate the process of grabbing users' profile information.
I'm sure many of us have had on a much smaller scale has an "oh crap" moment (formatting the wrong drive, etc, etc). But the process from seeing that spike to figuring out what is happening must involve a pretty substantial sinking feeling!