What does Ponyboy learn in the end with regards to his understanding of the Socs?

Ponyboy learns that the difference between the Greasers and the Socs is not as significant as he first believed.
When he first meets Cherry at the drive-in and talks with her, Ponyboy relates Johnny's terrible experience with the Socs in which he was severely beaten. Moved by the harm done to Johnny by boys she knows, Cherry says,

I'll tell you something, Ponyboy, and it may come as a surprise. We have troubles you've never even heard of. You want to know something?...Things are rough all over (Chapter 2).

Ponyboy perceives her as having a perfect life but later discovers that Cherry's boyfriend is Bob Sheldon, one of the Socs. Not unlike Johnny of the Greasers, Bob is also a victim of parental neglect although this neglect is due to leniency. His parents have set no perimeters for Bob, so he becomes wild. Bob later attacks Ponyboy at the fountain when he and Johnny are there late at night. Because Bob tries to drown Ponyboy, Johnny kills him.
After Johnny's death caused by the church fire that led to his broken back and other injuries, as well as the death of Dally, who commits a crime and gets shot by the police, Ponyboy realizes death does not discriminate against anyone. He also learns that families of all socio-economic levels have problems and children can be neglected in different ways.
In chapter 7, Ponyboy heads to the hospital to visit Johnny and Dally as the blue Mustang of Randy Adderson pulls up. Randy tells Ponyboy that he will not participate in the rumble between their two gangs. He explains that there is no purpose to a fight. Randy adds,

Greasers will still be Greasers and Socs will still be Socs. Sometimes I think it’s the ones in the middle that are really the lucky stiffs (Chapter 7).

Ponyboy has never thought that rich boys would feel "stuck" in their socio-economic class, but Randy certainly sounds fatalistic, not unlike some of the Greasers.
Later, Cherry will not go to see Johnny while he is in the hospital, because he killed Bob. She tells Ponyboy that Bob had charisma,

something that made people follow him, something that marked him as different, maybe a little better than the crowd. Do you know what I mean? (Chapter 9)

In his narration, Ponyboy admits that he does understand. He also realizes that Dallas is much like Bob:

Cherry saw the same things in Dallas. That was why she was afraid to see him, afraid of loving him. I knew what she meant all right (Chapter 9).

Ponyboy gains insight into life from his experiences, and he realizes that people are not as different from one another as he has thought.