Ultimately worker coops by their design limit the amount of excess money that can be siphoned off and concentrated to CEO's and shareholders, so capital holders would likely refuse to invest in co-ops in fear that were they to become the standard way of organizing businesses, they would get a smaller and smaller piece of the pie globally, as more wealth is distributed to the workers themselves instead.

The current system of capitalism is inherently designed to oppose all forms of more equal distribution of power and wealth.

If co-ops were to become successful in spite of that, the capital owners would likely attempt a military coup to literally fight back against it, just as they attempted during the Business Plot in response to FDR's economic reforms.

The capital holders hold a tremendous amount of the power to influence the globe to their will due to their concentrated wealth, which is only possible to accumulate due to the accepted exploitation of labor. They will do everything in their power to prevent the loss of that power, even if it means sub-optimal profits.