Bacon is an almost unique food, because it possesses six ingredient types of umami “savory”, which elicits an addictive neurochemical response in the brain. This is in addition to also stimulating the other tastes of salty, sweet, and ideally a slight bitterness.
The one missing flavor is sourness, which is why bacon goes exceptionally well with sour foods, and is also complementary to bitter flavors as well.