This Wikipedia page makes for interesting reading: https://en.m.wikipedia.org/wiki/PayPal_Mafia
“PayPal Mafia” is a term used to indicate a group of former PayPal employees and founders who have since founded and developed additional technology companies such as Tesla Motors, LinkedIn, Matterport, Palantir Technologies, SpaceX, YouTube, Yelp, and Yammer. Most of the members attended Stanford University or University of Illinois at Urbana–Champaign at some point in their studies. Several also attended the Illinois Mathematics and Science Academy during high school. Three members, Peter Thiel, Elon Musk, and Reid Hoffman, have become billionaires.
The PayPal Mafia are sometimes credited with inspiring the re-emergence of consumer-focused Internet companies after the dot com bust of 2001. The PayPal Mafia phenomena has been compared to the founding of Intel in the late 1960s by engineers who had earlier founded Fairchild Semiconductor after leaving Shockley Semiconductor. They are discussed in journalist Sarah Lacy’s book Once You’re Lucky, Twice You’re Good. According to Lacy, the selection process and technical learning at PayPal played a role, but the main factor behind their future success was the confidence they gained there. Their success has been attributed to their youth; the physical, cultural, and economic infrastructure of Silicon Valley; and the diversity of their skill-sets. PayPal’s founders encouraged tight social bonds among its employees, and many of them continued to trust and support one another after leaving PayPal. An intensely competitive environment and a shared struggle to keep the company solvent despite many setbacks also contributed to a strong and lasting camaraderie amongst former employees.