Sony isn't being greedy.
When Spider-Man joined the MCU, the deal wasn't meant to last forever. Sony scooped up the movie rights for Spidey back in the 90's when Marvel licensed their characters out to help make up for failing comic sales. The X-Men sold to Fox and Spidey went to Sony. Nobody wanted the Avengers. I bet industry executives are slapping themselves over that one. Now that Disney has bought Fox, the X-Men and Deadpool will be at home with Marvel once again. Sony and Disney entered into a joint venture to work with Spider-Man, but that deal will be coming to a close after a trilogy is completed.
One would think Sony wants to be greedy and take Spidey back, but Sony executive Amy Pascal wants the wall-crawler to stay in the MCU. “I think about crying,” Pascal told Vanity Fair when asked about Spidey leaving the MCU. "I can only hope for a future where things work out. I’ve known Kevin [Feige, Marvel Studios producer] since he was [Avi Arad’s] very, very quiet assistant, who for many years sat in that room listening to us and being so much smarter than any of us without any of us realizing. I will say that working with Marvel has been one of the highlights of my professional career." Feige and Pascal's relationship helped broker the deal between Disney and Sony, but the latter's ability to demand when the films drop has caused issues. For example, Sony making sure that Far From Home dropped in 2019 severely screwed with Disney's plan of keeping the details of "dead" Avengers under wraps.