Defined benefit pensions schemes ultimately need heavy regulation and a government backstop otherwise failure is inevitable.

That said, they can work great in tandem with the stock market.

The Kensington & Chelsea local government pension scheme in London, here in the UK, is an example.

The local authority (not central government) ultimately has the responsibility on paying out these liabilities, but it's one of the few councils that just dumped their pot in to global equities, and as a result they are 200% funded relative to their commitments and have stopped making further contributions.

The money that was flowing into the pension scheme can now flow in to local services.

Asset allocations:

https://www.ft.com/content/87c321ab-e5ac-4a1d-a637-c1f7befcc...

Cutting contributions:

https://www.ft.com/content/67254bff-0e6c-407a-a24a-c34ee217d...