The biggest reason is the American culture, they like violence and are entertained by it. They wet their pants watching men in medieval armour bumping each other, Nascar cars crashing each other and beating each other in the ring. It’s no coincidence that the overwhelming majority of the “extreme sport” fanbase are Americans.
Meanwhile, football is embedded in 80% of the world’s culture. There’s a reason why it’s dubbed as the “beautiful game” sport because cultures all over the world comes in and play in harmony. Football is accessible to anyone and gives hope to millions and brings people together like nothing else in sports. Like nothing else in the world. A single goal has a value and significance unlike other ball sports. It’s played by the brains.
Americans needs let go of this, nothing can beat football. It’s a global sport. The biggest and the most popular sport in the world.