A very important thing about individualist and mutualist anarchists that you completely omitted is that they are market socialists. They want an economy run by coops. By omitting this huge point, you described “anarcho”-capitalism. It would be lying by omission if done intentionally, though I believe that you have simply made an honest mistake.

A state is not the only way that people organize themselves and make decisions. A state forms when a person or group of people make decisions for the people in a given territory as a whole, and then impose these decisions on them through force or the threat of force. If the people make decisions collectively, without relying on kings, presidents, or senators and these decisions are not enforced by an unaccountable army/police force, then you have anarchy.

Under such a system, it is completely feasible to prevent the formation of monopolies, even if you still use a market. First, coops do not have as much of a drive towards monopolization that capitalist enterprises do. This is because the earnings of the decision-makers is not based on extracting surplus value from wage laborers. Second, if monopoly formation is noticed, then the next time the community holds an assembly, they can vote to break up the would-be monopoly.

Finally, individualist/mutualist anarchists would argue in favour of wealth redistribution. Recall that the rich have amassed their wealth through exploitation of the poor. It would be right to reverse such injustice.

You would do well to read the FAQ that the other guy linked. It talks about individualist anarchists too.