Maybe we should each have one micro business that we hang onto for life; that never gets shared with anyone, where we take no partners and never pledge it to a Bank for a loan and, thus, have something that is uniquely ours that we can fall back on in troubled times. “You need an iron reserve.”
There are so many changes going on in the local, national and global economy and so many things can and do go wrong, that it might not be a bad idea after all to have a fallback position.
A PB4L is a real business with real cashflow. Perhaps you are selling high-end, acid free paper or you have a series of organic food recipes that you sell at food fairs and in specialty stores or you have an online dino comic strip that you publish daily that becomes a hit.
Ideas are endless. Maybe you could look in the Encyclopedia Britannica circa 1932 for inspiration and public domain ideas.