Capitalism is commonly described as the system of private ownership (often rarefied as individualistic, though in fact it is corporate and collective). Its primary character is a system wherein selected corporations are given totemic symbols in their accounts (no printing press necessary) enabling them to order people and resources around. The primary creation of these symbols by commercial banks is the essence of capitalism. It requires collective action and legitimation far beyond the individual. This is far from just an assortment of individuals buying cheap and selling high. Markets are only a handmaiden of the essentially collective monetary system—collective, planned and centralized.
The private ownership of capital begs the question of where capital comes from in the first place. No individual Robin Crusoe ever created a unit of credit that can be subsequently traded for labor or iron. The very word capitalism suggests its essence is capital, a collective institution, not individualism. The common dichotomy of capitalism vs. socialism misses the point.