The youngest billionaires in the world in 2018

 Harvard dropout Collison co-founded Stripe, an online payment company, with his brother Patrick in 2011. The Irish-born brothers now live in San Francisco, where the company is based.
Stripe closed a $150 million funding round that valued the business at $9.2 billion in November 2016, according to Forbes.

5. John Collison, 27 — $1 billion (£722.1 million).