There is no evidence of cooperatives being capable of out-competing the megacorps of today in a system already controlled by megacorps. There is no growing systemic pressure for cooperatives to overwhelm megacorps, only further proletarianizaton and social stratification.
Nature tells you the power of cooperative working, look at ants, bees, fungi. The fediverse is a smack in the face of Reddit, Unix in the face of Microsoft. These things only grow, never shrink. There are more people in credit unions in America than any private bank. There are so many cooperatives in the agriculture space you wouldn't believe. Look up mondragon, the largest cooperative employer with over 70k employees. Look up IFFCO, the largest agriculture cooperative connecting farmers in India, which has a revenue of over $7 billion/yr. These are behemoths, a force for good. They are not being overwhelmed by megacorps, rather they overwhelm the megacorps.
Hey, I've argued this exact stance with my Marxist brothers a few times here and here. They seem sure of revolution and against market socialism. Anyways, I've created a community for us to talk more about it here - Collective Cake
And what a coincidence today being a Collective Cake day!