I'm not sure I follow your line of argument. Are you saying that competition produces coercive monopolies, and that the principle of nonaggression guarantees aggression? If so, that doesn't make sense.

The argument is not that humanity is magically good, but rather that the market process rewards virtue while the government structure guarantees corruption and destruction. Production and plunder are mutually-exclusive. Productive profit only occurs through mutual benefit. Politics is the process of plunder through coercive force to gain profit at another's expense. Centralized power guarantees the latter. Decentralized services reward the former.

“Anarchists did not try to carry out genocide against the Armenians in Turkey; they did not deliberately starve millions of Ukrainians; they did not create a system of death camps to kill Jews, gypsies, and Slavs in Europe; they did not fire-bomb scores of large German and Japanese cities and drop nuclear bombs on two of them; they did not carry out a ‘Great Leap Forward’ that killed scores of millions of Chinese; they did not attempt to kill everybody with any appreciable education in Cambodia; they did not launch one aggressive war after another; they did not implement trade sanctions that killed perhaps 500,000 Iraqi children. In debates between anarchists and statists, the burden of proof clearly should rest on those who place their trust in the state. Anarchy’s mayhem is wholly conjectural; the state’s mayhem is undeniably, factually horrendous.”

• Robert Higgs

"Anarchism is not a romantic fable but the hardheaded realization, based on five thousand years of experience, that we cannot entrust the management of our lives to kings, priests, politicians, generals, & county commissioners."

• Edward Abbey

"Anarchy is no guarantee that some people won't kill, injure, kidnap, defraud, or steal from others. Government is a guarantee that some will."

• Gustave de Molinari