This is beautiful and articulates terminology around contributions much better than the mush I’ve been kicking around in my head. :D

Yes, I love the starting principle of “everybody is being paid to work on open source”, unless you are literally unemployed and have no income coming in (which does happen, but is extreme). It’s about resource allocation, right — if a project requires more time, but time is in short supply (which can be for a number of reasons, for example, if an employer forbids a contributor to work on it during company hours and that contributor doesn’t have any time outside of work), then something needs to change to free up more time. So sustainability is really about enabling people to do the things they are already intrinsically motivated to do.