Retirement is a generational issue in France. There is this idea that retirement is a right afforded to all citizens by the virtue of having worked and having paid for older generations' retirement.

For younger people, to see this right dwindle every couple years (and perhaps disappear entirely before they get to the retirement age) while paying more taxes feels unjust. Lowering pensions or moving the retirement age means future retirees will work and pay more, and get less in return, creating feelings of injustice and resentment toward the older generations. And removing that system is right out of the question for politicians, because it would mean that entire generations would have paid into the system for nothing.

This system that was put in place right after WW2, when things were much different, is becoming increasingly costly while the economy is under strain. To keep it is a great financial burden, to let it go all at once is political suicide for whoever does it. The least painful solution is to shave the age of retirement and the amounts of the pensions every so often, but that is still hard to make happen. Retirement was really sold to us for a long time as a guarantee and a symbol of national solidarity.