Marvel only made this movie because it was in development for 8 odd years and they wanted to get it over with, the marketing wasn't as much as GoTG or AoU, you are really deluded if you think Marvel was banking on it hard, it was given a cold shoulder a lot of times by them, and they weren't even sure if this is phase 2 or phase 3, they just released it as a stand alone, I doubt they have plans of sequel
Each and everyone of the Marvel properties being released have a set purpose, AoU and Civil War are build up to IW 1 anad 2, Thor 3 and Doctor Strange are set to open the fantasy/magical element of MCU, Black Panther has the International/Minority appeal, The InHumans are the MCU's Mutants, GoTG introduced and developed Thanos/Infinity stone/ and the cosmic nature of the MCU plus it was their version of 'Fantastic Four', Daredevil introduces street heroes and the defenders, Captain Marvel shuts up the feminists, Spider-man is well Spider man
While Ant man is just stand alone, one shot movie