I think your second guess is the closest - but, I'd push you a bit further: Very few single mistakes are so big that that single mistake will doom a company, e

I think your second guess is the closest - but, I'd push you a bit further: Very few single mistakes are so big that that single mistake will doom a company, especially a company that's seeing a bunch of success and growth. In the Groupon case, I pretty quickly see two key mistakes: * not being willing to make a hard decision ("following the data" on short term metrics for something he said he knew didn't feel right as a long term decision) * not being able to keep an eye on the long-term and change course when needed. He frames this as "it happened too fast" but also makes it sound like this wasn't one decision, but a whole series of them. These are both classic new-leader mistakes, so maybe the version of Groupon that hadn't imploded in a parallel universe still made them but also learned from them just soon enough to prevent disaster. Mistakes are inevitable, how you respond to them matters just as much.