The question is about commercial closed source software. A lot of initial answers are about open source software. For me a key insight is that (for a certain e

The question is about commercial closed source software. A lot of initial answers are about open source software. For me a key insight is that (for a certain ethos of open source software) the most desirable contribution is technical or community rather than a financial contribution. "Bring your code, not your dollars." and "Become a partner in the product, not a consuming customer." Everyone else are the "freemium"-part of the model.