Yes, I took some rhetorical liberty in that last point. But even so, the fact that they are volunteers matter less that you seem to suggest: their rent and groceries were still paid for. Wether that came from parents, other benefactors or part time work or savings (being their own benefactors), the fact that they were at liberty to do what they did is a product of the changes we're seeing.

Or they did it as a hobby in their spare time?

"Spare time" is time that is left over when you've done the things you need to do. The existence of spare time is evidence that your productivity is higher than your consumption.