Jack Zhang was 34 years old, three and a half years into running a startup, and sitting across from one of the most powerful investors in Silicon Valley. Michael Moritz of Sequoia had invited him to his home — a place with, Zhang recalls, a couple of floors and a view straight to the Golden Gate Bridge — to make the case for selling. Stripe wanted to buy Airwallex for $1.2 billion. At the time, the Melbourne company had around $2 million in annualized revenue. The math was almost pretty