>>Having a bunch of private actors potentially run a huge experiment in which the economic fallout will not be born by them if it goes sideways is entirely unreasonable
The experiment is entirely opt in, with no one being affected that does not choose to be.
Of course its not; no more than the 2008 financial crisis was entirely opt in. Individuals do not have the opportunity to fully control all aspects of the financial system they're exposed to.
Individuals fully control whether they interact with the financial system at all, and if they do, which parts they are exposed to.
The risk posed by any financial asset is not distributed uniformly across the economy. Its impact on any party is proportional to their direct and indirect exposure to that asset, which is something that they control and have to take responsibility for.
The experiment is entirely opt in, with no one being affected that does not choose to be.