[zanny]

Capitalism is absolutely supposed to minimize costs, that is how competition works. It is more a consequence of economic reality than a function of capitalism that massive vertical integration and economies of scale can let market-spanning monopolies form.

But as others have said, unless barriers are put in place (economically natural like mindshare or opportunity cost or artificial ones like bribed legislation) the monopoly can't abuse their situation without opening up avenues for new competition to arise to compete with them.

On one hand, capitalism is obviously not optimal - a monopoly is only held to a price ceiling of what the most nascent newcomer is capable of. They are almost always able to take home the profit of their scale and integration even in the presence of competitors. On the other hand, the only way historically nations have battled this is to micromanage a market to guarantee enough strong entrenched and scaled competition to keep there from being a decisive market leader. But over time all markets trend towards that kind of centralization.