"From workers to retired people" implies at a casual reading that the worker and the retiree are not the same person, when in many systems the majority of what the worker pays goes directly to their own retirement.
It's debatable whether paying into your own account is a transfer of wealth at all, even if you're not able to withdraw your money until retirement.
You're still relying on money being worth something in future.
Imagine a future where there are half as many the workers as retirees. It doesn't matter how much money retirees have in their pensions if they cannot hire workers to look after them (do their healthcare, produce the food they eat etc). You'd just get rampant inflation as the richer retirees competed to get workers, and everyone else goes without. In other words, in that scenario the value of the saved money would be eroded by inflation.
Now I will admit that this is complicated by there being other countries, or if we invent humanoid healthcare robots or whatever. But there's a principle involved that someone (/ thing) has to do the work.
>You're still relying on money being worth something in future.
Yes, and that's why this basic pension can only be something guaranteed by the state. In case of war or massive devaluation or change or currency, the state (maybe not even the same one under which "rights" were acquired) can guarantee these things (and will want to guarantee them, in order to preserve the pensioners from poverty).
It's still all a clever scheme around the young looking after the old, numbers in an account wouldn't help us if everyone stopped having children today.
It's debatable whether paying into your own account is a transfer of wealth at all, even if you're not able to withdraw your money until retirement.