No, the economic incentive was not pensions, it was avoidance of death duties. It is precisely because Calment's family was wealthier that this motive is stronger:
https://yurideigin.medium.com/jaccuse-why-122-year-longevity...
https://yurideigin.medium.com/jaccuse-why-122-year-longevity...
I also like part 3 where he talks about the strange fact that the husband and son died of non-natural causes.
I have a feeling that Yvonne might have been quite the psychopath.
Great subject for a documentary.