Maybe unregistered securities is what I want to buy. What gives the government the right to say I'm not allowed to enter into a consensual agreement with someon

Maybe unregistered securities is what I want to buy. What gives the government the right to say I'm not allowed to enter into a consensual agreement with someone selling them? Why do I have no way of opting out of these protections unless I'm rich already? Sometimes it feels like I'm explaining water to a fish on here.