I'm not sure if i follow you.
But i will try to answer the best i can.
When i go to the bank, i may be participating in bank run, and i may the reason the bank collapses, and then the economy. My action of going to the bank does not usually causes that. But if you attempt to ban me from going to the bank because i may cause a bank collapse, it will certainly cause more harm then good.
And that's how we should look at the problem. The reason i have a principle that people should not interfere with my freedom to do as i chose (as long as i don't harm others), is because i believe that it will provide the best outcome possible, not the other way around.
That does not mean that there's no law that prevents two people of making a voluntary transaction that can give a better outcome than everything open. But it's just impossible to really know. The same reason your questions are hard to answer, if i disregard the principle, it will be hard to make such laws. So someone has to decide what becomes law, and what does not, and when that happens, those law will be imperfect, and you will have people who will benefit from some laws, and some who will be harmed. People harmed will not care so much for this imperfect and unfair system, and might as well ignore such (or other laws). People will also have incentives to make such laws, as they can benefit from it.
And you will never get a general agreement that such law will really do more harm than good, because people will have different views of that, rightly so. The law that prevents me from investing, may protect me from a bad decision, but will also prevent me from a good one. But as i am able to decide to get out of my house every day, and risk losing my life on a car accident, i should be able to decide what to do with what is mine. Even if some protection does look nice on paper, i do not believe i need to be protect from myself in a way that will limit my choices. If someone wants their choices be limited, just make it optional, and I will be able to decide if the protection is good or not. I doubt most people will really care about what people in the government think it is the right choice.