i am not defending anyone here, just that it irritates when you get stupid comments like keep taking the meds, that is not a grown up comment, nor is it any kind of response to the question.
As to the baby boomers, many are having to work on over the age of what would be considered retirement age, say 60/65. I know that the government has changed the ages, but go on past retirement guidelines. Those who have seen their private pensions plundered are having to make savings or simply keep on working. That isn't fair is it.
But back to the question, when you have a large influx of people, some of those may not be eligible to work, so not contributing, for example a man gets a job here, fine, but then he has dependants, wife, children, so one wage, but say 4 people, those other three will need housing, school places, hospital, so from one person paying into the system you now have four, maybe more to support. That is where it becomes unsustainable.