I doubt the majority of people watching the game are actually football fans. Besides that, there are plenty of people who watch solely for the commercials.
The majority of fans watching also don't buy Alfa Romeo's either. They buy Chevy, Ford, Honda, Toyota.
Here's something form an AP article last month about 2016 sales:
"Ford's F-Series pickup remained the best-selling vehicle in America in 2016, with 820,799 trucks sold. That's the equivalent of 93 trucks sold every hour. The Toyota Camry was the best-selling car, despite a 9.5-percent dip in sales to 388,618. Jaguar saw the biggest sales increase of any brand, with sales more than doubling over 2015 thanks to its new XE sedan. Fiat Chrysler's Italian brands, Fiat and Alfa Romeo, declined more than 20 percent each as customers scratched small cars off their shopping lists in favor of SUVs."
Notice what is said about the top selling vehicle and then at the end Alfa Romeo. I'd bet more people would pay attention to a Pick-up Truck or SUV ad than one for an Alfa Romeo.