City haven't been the biggest spenders - they've spent wisely and developed players. Many of the top stars didn't cost that much, compared to what other teams pay for players. Gundogan was 'only' 20m, Halaand was only 50m, Foden came through the youth academy. Other teams have spent significantly more and failed to deliver.
In fact, over the last 5 years ... we're only 10th in the list of highest spending teams. So sorry bitter-fan-of-whoever, you'll need to come up with something else.
https://www.football365.com/news/transfers-premier-league-five-year-net-spend-man-utd-man-city
On this table of net outlays, City are ranked 16th (I think the period it covers is slightly offset):
https://www.si.com/fannation/soccer/futbol/news/all-20-epl-clubs-ranked-by-net-transfer-spend-over-last-5-seasons
City have the highest operating income in the Forbes list of most valuable clubs (which doesn't yet factor in this treble winning season). Sort it by the last column (descending). Zero debt helps (compared to Man Utd). It's just a well run business.
https://en.wikipedia.org/wiki/Forbes_list_of_the_most_valuable_football_clubs
The bottom line is: of course money and investment helps, but throwing money at a soccer club is a good way to lose money - you can't simply buy success. City have built and developed over time, creating something sustainable, by looking at a longer time horizon than just the current season. The success on the pitch is supported by the well-run business off the pitch, both sides helping each other.