What has powered open source to become part of 75% of all software and drive nearly €100 bn of GDP in Europe? Reuse, yes. But that was always possible. Collaboration, definitely. But repositories existed for years before open source was coined in 1998. The software freedom philosophy. Absolutely, but that went 15 years without triggering a software revolution. I suggest it's something less measurable and observable — developer confidence — and that the effects involved are stochastic, not deterministic.