Define "personal upside" because people work hard all the time absent a path to power, or even material benefit! Come to think of it, why do people have children?
Humans are social animals and they are deeply moved to work extremely hard for the sake of love, dignity, and respect alone. Contrary to the nonsense picture you paint, humans only lose touch with such desires in the face of hopelessness to realize them.
This is bullshit, and obviously so. Humans are by nature lazy. If you give people food and comfort, they will work the barest minimum they can to not be bored, and practically speaking, they'll pick an unproductive hobby (like gaming or idle art) instead of the stuff that society needs to function.
People have kids because having a kid is a deeply rewarding experience. Very few people are going to volunteer to work in mines, maintain sewer systems, or farm for other people to eat.
"Co-op". It's in the name. Reciprocity? Community? There is personal upside, just not the HN-approved shareholdery kind.
Enough personal upside to get someone to build you a house? Clean out the sewers? Wake up at 4AM to sit on a tractor and plow a field?
If you think the answer is yes, then why don't you try and get some people to do those things for "reciprocity" that doesn't involve money?
But there's a reason why co-ops are rare outside of that: why would people work hard without personal upside?