Manchester City already has the strongest squad. But they are not afraid to spend money if necessary. They paid 75 million Euro for Marmoush just 5 months ago. You seem to forget that quickly.
Their transfers of Reijnders, Aït-Nouri and Cherki so far total 127 million Euro. That's not a small amount of money. They are still a team that spends big money. With that comes success, last season was an exception.

City alone is already spent almost 240 million pounds this year. It's almost doubled than what you have stated above. This is the main recipe to build a winning club. Spending a lot of money is a must to form a quality squad.
Kinda weird when people called City spent nothing. Meanwhile, it's a common knowledge that big team's success is money.