Earlier quoted context omitted.
Perhaps somethings are more valuable than money to some?
Money isn't what we're optimizing though. It's freedom. Having a software product as income source means you don't have to have a day job working for somebody else. It means you can spend your time doing whatever you want, be that working on your own personal projects, surfing, traveling or, yes, earning more money. You can even choose to build open source Mac text editors and give them away for free. It's your choic…
One explanation, like you point out, is that they are free to work on a project such as CotEditor because they are financially secure.