But surely your time was worth something. Isn't that the first lesson of running a business -- pay yourself first?

If you're doing something you really love, money is just a side effect.

Loving what you do never bought groceries. So the actual answer has to be 'I have enough money from other sources to live on'.

Perhaps they draw fixed salaries from the business as a whole, and since they'd intended to donate the proceeds of this particular project to charity anyway, they didn't see any point in allocating any portion of their sunk fixed costs to it. Note that they didn't include rent, electricity, etc. either.

The money spent on essentials may also be essential, but things can both be essential and the side effects of processes which have some other primary intent.

I'm not sure why you don't get this, but there's a huge gap between not having money be the primary intended result of your actions and having money not at all be a result of your actions.