PayPal was founded in 1998 and sold to Ebay in 2002. Several of the key members have since become billionaires, founded companies such as Tesla, LinkedIn, YouTube, Yelp and/or seed invested in Facebook.
I copied the list of PayPal members, coined the PayPal Mafia, from Wikipedia and added their ages in year 2000:
- Peter Thiel (born 1967; 33 years old), PayPal founder and former chief executive officer who is sometimes referred to as the “don” of the PayPal Mafia
- Elon Musk (1971; 29), is founder of X.com which acquired the company Confinity. Musk later co-founded Tesla Motors, SpaceX, OpenAI, The Boring Company, and is the Chairman of SolarCity
- Reid Hoffman (1967; 33), former executive vice president who later founded LinkedIn and was an early investor in Facebook, Aviary, Friendster, Six Apart, Zynga,
- Luke Nosek (1976; 24), PayPal co-founder and former vice president of marketing and strategy, became a partner at Founders Fund with Peter Thiel and Ken Howery
- Ken Howery (1975; 25), former PayPal CFO who became a partner at Founders Fund
- Keith Rabois (1969; 31), a former executive at PayPal who later worked at LinkedIn, Slide, Square, and currently Khosla Ventures, and personally invested in Tokbox, Xoom, Slide, LinkedIn, Geni, Room 9 Entertainment, YouTube, and Yelp.
- Max Levchin (1975; 25), Founder and chief technology officer at PayPal sometimes called the “consigliere” of the PayPal Mafia
- David O. Sacks (1972; 28), former PayPal COO who later founded Geni.com and Yammer
- Scott Banister (1975; 25), former Ironport CTO and PayPal board member
- Roelof Botha (1973; 27), former PayPal CFO who later became a partner of venture capital firm Sequoia Capital
- Steve Chen (1978; 22), former PayPal engineer who co-founded YouTube.
- David Gausebeck (?), former PayPal Technical Architect, co-creator of the Gausebeck-Levchin test, co-founder of Matterport Inc., a digital 3-D modeling company.  IronPort, Flickr, Digg, Grockit, Ping.fm, Nanosolar, Care.com, Knewton, Kongregate, Last.fm, Ning, and Technorati
- Chad Hurley (1977; 23), former PayPal web designer who co-founded YouTube
- Eric M. Jackson (1976; 24), who wrote the book The PayPal Wars and became chief executive officer of WND Books and co-founded CapLinked.
- Jawed Karim (1979; 21), former PayPal engineer who co-founded YouTube.
- Rod D. Martin (?), former special counsel to CEO Peter Thiel whose 10X Capital took over Galectin Therapeutics in 2009 and who founded Advanced Search Laboratories in 2012.
- Dave McClure (1967; 33), a former PayPal marketing director, a super angel investor for start up companies and founder of 500 Startups which has hit 500+ investments. 
- Andrew McCormack (?), co-founder of Valar Ventures 
- Jason Portnoy (?), former vice president of financial planning and analysis who later became CFO at Peter Thiel’s Clarium Capital, CFO at Palantir Technologies, and founding partner at Subtraction Capital.
- Jack Selby (?), former vice president of corporate and international development at PayPal who co-founded Clarium Capital with Peter Thiel, later becoming managing director of Grandmaster Capital Management.
- Premal Shah (1975; 25), former product manager at PayPal, became the founding president of Kiva.org.
- Russel Simmons (?), former PayPal engineer who co-founded Yelp Inc.
- Jeremy Stoppelman (1977; 23), former vice president of technology at PayPal who later co-founded Yelp, Inc.
- Yishan Wong (?), a former engineering manager at PayPal, later worked at Facebook and became the CEO of Reddit.
- Youngest is 21
- Oldest is 33
- 6 are in age group 20-24
- 7 are in age group 25-29
- 4 are in age group 30-34
- 7 are unknown
- 3 of 6 billionaires in age group 30-34
A 2007 Forbes sheds some light on the hiring process:
Many of PayPal’s early hires matched a specific profile: highly intelligent workaholics who were good at math. No frat boys, MBAs, or , God forbid, jocks.
“The difference was that Google wanted to hire Ph.D.s,” says Roelof Botha. “PayPal wanted to hire people who got into Ph.D. programs and dropped out.”
After the merger with Elon Musk’s X.com in 2000, PayPal must have been a very stressful environment full of intrigue. Despite this, they kept the ship afloat and eventually sold the company for $1.5 billion to eBay in 2002. Elon Musk, the largest shareholder, received $165 million.
It’s an interesting case and I’d like to read The Paypal Wars – if I can get a copy. It’s unavailable at Book Depository.
I don’t want to draw any conclusions but there are some good lessons ( as I see them):
- Revolutionary tech? Hire young guys – the hungry, math minded kind
- Internal struggles? Not able to overcome them? No shame in selling out. Someone else can restructure and grow it big
- The experience is valuable – next time you do better!
- The network you obtained can make the difference next time – don’t lose your invaluable contacts!