You’re moving the goalposts. My reply was to net spend since Guardiola took over at City, not since SAF’s retirement.
Regardless, City have spent £1.074 billion since Guardiola arrived. United have spent £1.077 billion since then. On a net basis, City have spent £478 million while United have spent £835 million.
Click here for source.
Over that period, as I mentioned above, Liverpool and Chelsea both managed to beat City to the Prem and UCL among other trophies whereas United have not. And in the case of Liverpool, it’s despite spending a fraction of what either City or United spent. This tells you that spending frivolously is no guarantee of success.
If you want to talk about manager churn, then why has Chelsea been more successful than United over that period despite having Conte, Sarri, Lampard, Tuchel, and Potter. That’s 5 managers since Mourinho was at United.
You can cry foul all you like about City’s (alleged) financial doping, but the issue for United is that they are a very poorly run organization with an owner that cares more about lining their pockets and the status associated with owning one of the largest sports franchises in the world. Until that is fixed, you can spend 100x what City spend and it won’t make much of a difference in the on-field results. Other clubs have found ways to beat City despite smaller budgets.