Earlier this week, Buffett’s Berkshire Hathaway invested $500 million into the company, now one of the world’s most valuable startups with a private valuation of over $25 billion.

Nubank co-founder Cristina Junqueira said Wednesday during Fortune’s Global Forum conference that she speculates Berkshire “saw an opportunity to stay ahead of a trend that we’re seeing all over the world of digitization, more and more so.” The digital bank, which operates no physical branches, now has about 40 million customers.

Of Brazil’s population of 200 million, over 16 million people do not have bank accounts, a phenomenon Junqueira attributed to “people just feeling embarrassed and out of place of coming to a bank branch.” She explained that customers may be put off by the “very hostile experience” of visiting a Brazilian bank office, which could contain bulletproof glass, metal-detection systems, and armed guards. 

“A lot of people feel that they’re being treated like criminals when they get into a bank branch,” Junqueira said.

As to whether Nubank is considering going public soon, Junqueira said “That’s the million-dollar question.”

“I get that question, literally every day, at least like 10 times from different people,” Junqueira said. “It’s definitely in our future… but we’re not in a hurry.”

About Facebook offering ways for people to access financial services via its WhatsApp chat app, Junqueira dismissed the idea that it would pose a competitive threat.

“We’re partners of WhatsApp,” Junqueira said. “We’re one of the first companies to partner with them to allow WhatsApp Pay to be available to our customers and we’re all for options that are going to bring more convenience and efficiency to our customers.”