One does not have to retire to a first world country. Seriously, why would you even want to retire to USA? Health care, which old people tend to use, is stupid expensive.
Family. Literally everyone wants to retire near their family, kids, and grandkids.
Yes, those rights being the sole right to purchase health care. Which can be very good if you have money and doesn't exist if you do not.
But do all nations actually have that?