This is a horrible way to frame the study's finding. "1% of people are responsible" sounds like some group is wasting resources, or taking up an uneven share.
The study looks at one year, and finds in that one year 24% of spending was on 1% of the people receiving care. That's not very surprising. 30 years ago I was in a bad car accident. I'm sure the cost of the ambulance, the emergency surgery, and the after-care was WAY more than most people average that year, and easily the most expensive medical year of my life. But it was just that one time.
The study looks at one year, and finds in that one year 24% of spending was on 1% of the people receiving care. That's not very surprising. 30 years ago I was in a bad car accident. I'm sure the cost of the ambulance, the emergency surgery, and the after-care was WAY more than most people average that year, and easily the most expensive medical year of my life. But it was just that one time.