The SSA OIG has done a couple of investigations into this the past decade. In 2023 [0], it agreed with the SSA that "almost none of the numberholders discussed in the report [people aged 100 or older] currently receive SSA payments" (while disagreeing that the costs and risks of a mass correction effort outweigh the benefits)

> While we agree that adding presumed death information to these records will result in incorrect dates of death appearing on these Numident records, we do not agree it poses a significant risk of erroneously recording death information on living numberholders’ records. For example, we see little risk in adding presumed death information to the millions of Numident records belonging to individuals born in the 1800s who haven’t worked or received SSA payments in more than 50 years.

> SSA determined the estimated $5.5 to $9.7 million in expenditures to correct these errors was too costly to implement and that the effort would have limited benefit to the administration of SSA programs. We acknowledge that almost none of the numberholders discussed in the report currently receive SSA payments. However, SSA issued each of these individuals a valid SSN and these SSNs could allow for a wide range of potential abuse.

[0] https://oig.ssa.gov/assets/uploads/a-06-21-51022.pdf#page10

> Japan found over 200k ghost centenarians in their database

Weeeeeell.... https://cnrs.hal.science/hal-03478634/document

> Why?

150. I already said this.

The children of a 150-year-old would probably be in their ~120s. The grandchildren would be in their ~90s.

You're claiming a social security account that's been passed down through multiple generations, like some kind of family heirloom.

It's an extraordinary claim, if you get my drift.