To which you added a 2nd statement that made a wide generalization: “Being a sports fan is part of American culture… not so much in Canada”
What does your second statement have anything to do with the US “stealing” a sport? You made a blanket statement whereby you panned Canada’s support of sports — I merely addressed that second generalization.
As Estimated Prophet posted - the tribal aspect of U.S. society extends to all aspects of life including sports, hence, the extreme focus in all organized sports elementary school level through college - that focus also includes sizable attendance at amateur sporting events.
As an example they sell out NHL arenas for high school hockey tournaments regularly let alone state / college tournaments.
Mtl can’t sell out Bell Centre for WJC, let alone other amateur sporting events or non Habs events. It’s not good or bad, one is not better than another, supporting sports teams from amateur to pro is just a difference in cultural mindset & that difference led to creation of interest in basketball when James Naismith moved from Mtl to Springfield College and later to U of Kansas where he started the Jayhawks basketball program