You could have enforced diversification (certain percentages allowed for high vs. low risk), and accreditation boards to vet and approve mutual and index funds.
Also, the investment would have a very stimulative effect on the economy, and you could probably also set it up in such a way that it works on autopilot (like a 401(k)) for those that can't be bothered..
It would be quite a bit less draconian than the government simply confiscating the money. In the private sector, the current setup would rightly be called a ponzi scheme.