In the early stages of building a company, founders often temper their expectations and make conservative projections about future success. DoorDash cofounder and CEO Tony Xu now cautions entrepreneurs against capping their ambitions—a mistake he once made himself.

"I think a lot of times you kind of, as an entrepreneur, have to take the greedy algorithm," Xu said on the Uncapped with Jack Altman podcast. "You have to keep going all the way and seeing if there's more."

The lesson stems from his experience securing seed funding for DoorDash in the spring of 2013. Just months after the company's launch, with roughly 150 customers and $10,000 in sales, the four cofounders applied to start-up accelerator Y Combinator, whose alumni include Airbnb, Stripe, and Reddit. When asked how much revenue they believed the business could eventually generate, the team offered a figure that felt aspirational at the time but now appears strikingly modest for a company valued at $87 billion.

"I estimated something like $100 million of revenue," Xu continued. "Thankfully, we're a few orders of magnitude off."

DoorDash actually reached that annual revenue mark in 2018—and has accelerated sharply since. First-quarter revenue this year reached $4 billion, roughly 40 times the founders' original full-year projection in a single quarter. The company overtook earlier entrants such as Grubhub to become the largest food delivery platform in the United States, as widespread smartphone adoption and shifting consumer habits fueled demand for on-demand delivery services. The company's growth has extended well beyond its Silicon Valley origins: total orders across the United States and more than 40 other countries grew 27% year-over-year, reaching 933 million.

"It's very hard as an entrepreneur when you're working out of your apartment, to know what that size could be one day," Xu said. "Turns out a lot of people eat food."

Founders Say Being 'Delusional' and 'Crazy' Is Essential

Founders who have built billion-dollar businesses are increasingly candid about the unconventional mindset behind their success. Whether described as "delusional" or "crazy," many credit embracing bold, unconventional thinking as a key driver of their achievements.

Chess.com cofounder Danny Rensch launched his online platform at a time when his personal life was near collapse. Although he initially doubted his own vision was realistic, he attributes part of Chess.com's success to a degree of self-delusion. After years of sustained effort, Rensch scaled the platform into a premier destination for digital chess, reaching a $1 billion valuation in 2023. Today, the platform hosts tens of millions of matches daily, with hundreds of millions of users worldwide.

"The idea that Chess.com could actually be what I thought it could be required me to be delusional," Rensch told Fortune last year, echoing the perspective of his friend, Bonobos cofounder Andy Dunn. "The belief that you see something that doesn't exist yet, and how delusional that is, is the requirement for every successful entrepreneur."

Billionaire Mike Repole argues that a degree of craziness is essential to entrepreneurial success. The serial entrepreneur cofounded and sold beverage companies Glaceau (Smartwater, Vitaminwater) and BodyArmor to Coca-Cola for a combined $9.7 billion. Along the way, he acknowledged failing multiple times. With roughly two-thirds of start-ups shutting down within a decade, Repole stresses that founders must persist even when circumstances encourage retreat.

"The first five years for an entrepreneur, I call the survival years. Every single day, you could go bankrupt," Repole said in a 2025 interview with the School of Hard Knocks. "I started crazy…Crazy people change the world."

George Arison, a veteran entrepreneur and CEO of the LGBTQ+ dating platform Grindr, told Fortune that being "arrogant and crazy" is a prerequisite for founders aiming to succeed in the United States. Arison embraced both qualities, driven by a motivation to accomplish what appears impossible. Grindr now holds a market cap of $3.2 billion and continues to grow rapidly year-over-year.

"One of my motives in life is doing impossible things; that's how I've shaped my life," Arison said at Fortune's 2024 Brainstorm Tech conference. "My whole life is impossible; I'm now here doing this, and look at where I was born. Nothing's actually impossible."

This story was originally featured on Fortune.com.