That seems normal since so many people die at the end of their life. You wouldn’t expect expensive, life saving procedures to take place in the middle of people’s lives.
Since many don’t succeed those costs pile up and count in your stat. But many do succeed do people’s lives are extended.
A quick google and a few articles seemed to agree E.g.
"Spending during the last twelve months of life made up a modest share of aggregate spending, ranging from 8.5 percent in the United States to 11.2 percent in Taiwan, but spending in the last three calendar years of life reached 24.5 percent in Taiwan"
But how would you know? You could be a healthy 74-year old and think, "well now is the time, before I go down hill". But you could be cutting off 10 or even 20 years of life in decent health.
Or you could wait until you start to get sick, but how would you know it's not just short-term? You could have a case of pneumonia but recover in a month, and again go on for another 10 years. I've seen a fair number of elderly be sick for most of a year and still come out of it: A relative recently passed at 94, but around 86 she had some serious health issues, and her fate was very uncertain. But she beat them, and had another 8 years where she took great joy in seeing multiple great-grand nieces & nephews born, swim in her pool, listen to her read them stories, etc. They were some of her happiest times, but would have never happened if she'd been trying to beat the 18-month decline.
Because dementia runs in mom's family. Shes getting it and is aware of it, so if I get it I should be aware of it also. At some point its time to pull the plug.