They might be net positive for the workers within the co-op (at the median anyway) versus taking on outside investors and giving them a slice in search of large

They might be net positive for the workers within the co-op (at the median anyway) versus taking on outside investors and giving them a slice in search of larger scale. For diversified investors, it's more valuable to have some of your companies return higher gains even if others don't work out. For an employee though, their income is totally concentrated in their one job. The employees can be rational in not wanting investors, and the investors are rational in not wanting to invest in those firms (at terms the co-op would accept).