I also don't understand the greed by Manchester City... They've already signed James Trafford for 30m euros. They have a backup goalkeeper who is Ortega also.
Then why are they going for Donnarumma too?

I don't think Trafford would be happy about giving his starting eleven place to him.
I'd rather see Manchester United going for the Italian goalkeeper as they need the most now.
Greedy? What greedy are you referring to here, a team is trying to sign players in sensitive areas and you're saying they are greedy, no they are not. Manchester City or should I say Pep is no longer comfortable with Ederson in front of goal and wants a chance that's why they are pushing hard to get Donnarumma from PSG before the window closes. Ortega is not even in City's plans and their new goalkeeper can't start handling first team matches yet that's why they are going for Donnarumma.
I won’t say adding Donnarumma to the city squad is Greed, for all we know Ederson is either leaving this summer or won’t be the first Choice for Manchester city this season. For sure trafford was bought this summer but with you can’t expect him to be in charge for the premier league, champions league and even the FA Cup for Manchester city, maybe that was the plan for him to be in charge but if there is an opportunity to sign a good and experience goal Kepler then why not.
We all know how competitive the league will be this season, with pep going trophyless last season I don’t think he would want to take chances again. He needs to win something this season and a good and experience goal keeper will be a good place to start.
The club may not have much confidence in Brazilian goalkeeper Ederson, and the goalkeeper they brought to their club last season is not able to perform the role of the main goalkeeper well, which is why Manchester City is thinking of bringing Donnarumma to the club. I don't know if this deal will be successful, but if Donnarumma comes to Manchester City, then Manchester City will not have to worry too much about Manchester City's goalposts.
Now, after having good players in every position of the team, if there is no good goalkeeper in the goalkeeper position, then no matter how well the players perform, success will never come as a team. Now, if Manchester City offers Donnarumma, how much interest Donnarumma will show in coming to Manchester City is also a big issue because Donnarumma won the Champions League trophy with PSG last season, so PSG will try to keep him at the club even if they increase his salary.