Attention entrepreneurs looking to “wow” Ben Horowitz—he’s not interested in your perfect elevator pitch.

In fact, he says that big ideas don’t come in perfect packages.

“We’re not really looking for great ideas,” Horowitz says. “We are looking for really good ideas that look like really bad ideas.”

The “we” he refers to is $2.5 billion powerhouse venture capital firm Andreessen Horowitz, which he runs with his partner of nearly two decades Marc Andreessen. And as Horowitz tells it, the hottest duo in Silicon Valley won’t be swayed in five minutes.

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“You have to spend time with the entrepreneur to understand the secret they have and how they earned it,” Horowitz says. “That never happens in five minutes… it’s not a movie script. It’s a breakthrough idea that’s going to change the world.”

And the entrepreneurs the firm has invested in have, without a doubt, changed the world. From Facebook to Twitter to Github and Pinterest, Horowitz says what he looks for in a leader worth investing in is someone brave enough to stand up for what they think is a great plan, even if others disagree.

“The biggest mistake, by far, [when pitching] is telling me what I want to hear, or what they think I want to hear,” Horowitz says. “Them listening to me, and thinking ‘Oh, he wants to hear this,’ and changing their idea to match what they think I want. It always breaks down through the pitch and winds up being inconsistent with their own thinking…. What we are looking for are people who have breakthrough, original ideas, and the courage to say, ‘I believe this, even if you don’t.’”

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And being an entrepreneur with conviction is never a smooth ride, as Horowitz chronicles in his book, The Hard Thing About Hard Things. It leads to two conflicting emotions when building a company—euphoria and terror.

“My most vivid memory of terror was when our largest customer at Loudcloud called to tell us they were going bankrupt, and owed me $25 million—that was pretty much guaranteed bankruptcy for me. I was pretty worried,” he says. “But euphoria was when I figured out how to sell the cloud computing company [Loudcloud] to EDS, and we signed that deal.”

Another moment of terror? Being told to “f-off” by Andreessen, when Horowitz was starting his career at Netscape, where Andreessen was founder and chief technology officer.

“I was worried about losing my job, because I had three kids,” he says. “But it taught me a really important lesson. “The Godfather” said it, and did it a disservice, that ‘it’s not personal, it’s just business.’ But business is very personal. It’s important to learn how to not take it personally.”

But today when Andreessen and Horowitz butt heads, it’s no longer a big deal.

“I am used to it—he gets mad at me, and I get mad at him,” he says.

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