How does a business get off the ground without investment? Other than taking out a loan, credit card debt, or personal savings
You’re correct that financing is harder compared to VC funding, and likely involves personal or bank loans.
You've hit on the largest challenge of starting a co-op, that is getting the initial investment as it is quite difficult to get those loans and there are not as many investors pursuing that route.
This article from a couple of weeks ago hits on how it's actually getting harder for them. https://www.propublica.org/article/the-government-is-here-to...
Also, some cooperatives are cooperatives of other businesses (agricultural coops are often this, and sometimes sports leagues or similar), but those are in some ways a very different thing.