Since the investment started, City won 2 titles in the initial 6 seasons. Since Pep came in they are on course for 4 in 6. It's not just the style.
It's not like they were light spenders earlier either. First two seasons they got expensive stars: Aguero, Dzeko, Balotelli, Tevez, David Silva, Yaya Toure, Adebayor, Nasri as well as expensive average players like Hart, Barry, Milner, Clichy, Sagna, Kolarov.
I also don't think the "2 first XIs" is true, at least since Aguero declined/left.
They have pretty average depth in forwards: Jesus, Foden, Sterling, Mahrez, Grealish for 3 positions. United have one more, and with much bigger names.
Defenders are well-stocked but nothing extraordinary outside some price-tags: Stones, Dias, Laporte, Ake at CB, Zinchenko, Walker, Cancelo as fullbacks. Technically United have two more! (5 CBs, 2 LBs, 2 RBs)
Midfield is also good but not insane spoilt: Rodri, Gundogan, Bernardo, KDB, Fernandinho. One less than our wretched midfield options!
Overall I don't think it's excessive (again, apart from some prices).