I understand the current system, I just think it's not a good one. It seems to be designed on the idea that there will be an ever greater pool of young people who will support the people who are at retirement age. If that assumption is incorrect (and it currently seems to be incorrect) the current seniors don't have enough to retire.

It would make more sense if the system was designed similar to an individual retirement plan, except pooled for everybody of a certain age. So, you paid into the system throughout your life, then withdrew money when you retired. In a system like that it wouldn't matter if there was a population boom or a population crash when you were getting older, because the only thing that mattered for your retirement were the contributions you (and everyone else your age) made during your life.

Undoubtedly it would be hard to switch to that kind of a system, but it makes so much more sense than your retirement depending on the contributions of future generations.