There are many elderly parishioners at my parish. Their mass attendance hasn’t changed. They have always prioritized their faith and have large families who do the same. What you are seeing are young people who worship themselves and are largely depressed and demoralized. I say this as a millennial who sees it very plainly in people in my age group. This is a generational change in priority, not a new trend in old people. Additionally, this is 4 times per year at the high end. This chart seems to intend to highlight how many people attend never or almost never.