Not sure why you're being downvoted, but this is exactly how investments work. You keep contributing even when SHTF because nuances of your investments notwithstanding, you're buying $500 shares for $50.

There's a point where given average annual returns of x% over any given ten-year rolling period, the pension becomes self-funding. If employees are vested for y # of years, it becomes impossible for any employee to withdraw more than their contributions (and the resulting compound interest) contributed to the fund.

Pensions are fundamentally sound. It's corruption and mismanagement that kills them.