I think this argument loses a lot of nuance. The idea behind anarchism, I think, is that people will generally be good to each other and support each other when left to their own devices. In fact, if you think about it, the capacity for doing harm is only very large when you have highly centralised power structures. The fact that people aren't perfect and can do harm at all means, to anarchists, that we should not give the power to cause widespread harm to any individual or small group.

As for the COVID example, we are being told that the disease is spreading because of irresponsible people congregating in bars and salons etc. But if you look at the numbers, the main places that the disease is spreading is in workplaces like meat factories. People are not going to work in these places and spread the disease because of some "selfish, egotistical" inclinations. They are doing so because the society we live in has selfish people with a lot of power that are willing to get others infected for the sake of profit -- i.e. the business owners who are forcing people to work in unsafe conditions if they want to keep their jobs. I think this is further evidence that anarchism is a better approach.