Nobody is denying that quality players (can) cost big money.
I'm merely denying your original assertion that a team will be successful in a particular season because they've spent a fortune on a player (singular), and pointing out that it's not guaranteed.
You now say
The point is if you want to buy quality players they will cost big money - That's how both City and Chelsea have reached the top - by spending big money on players
Shifting your point to encompass the purchase of a number of quality players (plural) over several seasons is a different argument, and one that I wouldn't necessarily disagree with even though a case could be made against it.