The government’s primarily, but theirs too because they are the govt., or at least their cohort, friends and neighbours.
The proper thing to do is raise the retirement age to 75, reflecting gains in longevity and economic reality. Other options include some form of part-time mandatory volunteering component to earn the govt. portion of the pension.
However we do it, we are breaking a promise, if you will, that society made to these people when they entered the work force, in that if they endure the indignities and inequities of a salary/wage position for 35 years, then they have earned the freedom to spend the remainder of their time as they see fit.