It is the nostalgia trend. The story is recent enough for old people like me to remember and old enough that the millenials never heard of it, so it will get both age groups to go see it. Kind of like the Bobby Riggs vs Billy Jean King story.
Nancy Kerrigan grew up and lives in the town adjacent to where I live. The Boston Globe had an article today where they called her and asked what she thought about the renewed interest in the Tonya story. She basically said she's just ignoring and going about her business. She's made a good life out to figure skating whereas, Tonya has done everything from celebrity boxing to World's Dumbest..... to try to make a buck.