You can be a superstar and still not succeed alone, without other superstars around you. They are so successful because they know each other. And survivorship bias guarantees that all those who didn't make it are unknown, or not mentioned.

This is the role of successful companies like this, just like top universities. They help create the connection between people with huge potential (or money), superstars, and amplify it.

Remember those pictures will all the famous 20th century geniuses in one place. They each got to reach the peak by building a new step on top of someone else's previous step, and so on. Eventually they all climbed the same ladder together. They were like a talent packed sports team dominating the sports for many seasons. It's not a coincidence they're in the same picture.