Wences Casares has been called the “patient zero” of bitcoin among Silicon Valley’s elite. He got Bill Gates, Reid Hoffman, and countless other luminaries into bitcoin at gatherings of the rich and famous in Sun Valley and elsewhere.

The Argentina-born Casares has founded an internet service provider, a video game company, and a bank, plus he sits on the board of PayPal. But it’s bitcoin that Casares says he’s dedicating the rest of his life to, and he now runs a startup called Xapo that stores bitcoin. At a dinner organized by the cryptocurrency policy group Coin Center in New York last night, Casares delivered the keynote speech, including the advice he doles out to people who ask him how to get into bitcoin.

The formula, according to Casares? Take 1% or less of what you own, buy bitcoin with it, and then forget about it for at least the next five years; ideally the next decade. “You either lose one percent of your net worth, which most people can take, or you make millions,” he told a room of cryptocurrency advocates at the Westin in Times Square.

Casares pegs the odds of bitcoin failing completely and going to zero dollars at 20%. “If it fails, it will be worthless,” he says. “If it succeeds, in five to seven years it [one bitcoin] will be worth more than a million dollars.” He puts the chances of success at greater than 50%.

Casares says he’s seen people who bought bitcoin at cheap prices—as low as $13—lose out because they tried to trade their way to profits, while those who bought at high prices have done “spectacularly well” by simply buying and holding.

A world where bitcoin is $1 million a coin will reflect its status as the world’s “meta currency” and a “global standard of settlement.” “The world used to have a global standard of settlement for 5,000 years and it was gold,” he says. “If you wanted to compare how much it cost Cleopatra to put together an army to how much it cost a Chinese emperor, it was straightforward. We don’t have that today.”

Whereas gold was difficult to settle, requiring cumbersome storage and transport, it’s “trivially easy” to do so with bitcoin. “If bitcoin succeeds I believe it will be the biggest leap forward in the democratization of money we have ever seen,” Casares says.