Competition between firms, as Marx argued in 1844, ensures that capital will concentrate into fewer and fewer hands, while the rest of us will sink downward, lose our property, and become wage workers. Populists would argue that this gives small capitalists a bad rap that many shopkeepers, consultants, small farmers whom they know are kindly, benevolent. But to be sustainable, every single small capitalist would have to be a saint, would have to give away his profits to his competitors and to the community if he started winning too much at their expense. That is impossible. With competition for profit, most such cooperatives will eventually go under, while a few will survive.
Competition always intensifies, because the rate of profit tends to fall.
Capitalists, big or small, cooperative or corporate, compete with each other on the market, and they do so by cutting their prices. The best way to do this is to replace their workers with machines. But then his surviving competitors get the same technology. Since profit is based upon human labor, profits, in general, fall, as they get squeezed between falling prices and higher technological costs. As profits fall, competition for profits intensifies.