And this is a big part of the reason the majority of pension systems in Europe are going to be bankrupt within 10 to 15 years. (The other part being the inverted population pyramid)
And state pension schemes are not usually investment based at all. They are usually funded by current social security contributions and taxes. If they go bankrupt it's for political reasons.
More likely than bankruptcy is that many people will receive lower pensions than they had hoped for.