At 17, he bought a sandwich shop for $125,000 -- he renamed it Jersey Mike's and just sold it for $8 billion

At 17, Peter Cancro bought Mike's Subs with a loan, later renaming it Jersey Mike's Subs. Blackstone now plans to acquire a majority stake, valuing the company at $8 billion and making Cancro a billionaire with a net worth of $7.5 billion.