Managing a company's culture is an extremely nuanced process. There are plenty of brilliant startups that experience massive growth only to fall apart when they get too large.
We came across a great TEDx talk, "First Why, Then Trust," that explains why this happens. Simon Sinek, author of Start With Why and professor of strategic communications at Columbia University, starts out by explaining that trust is the basis for how communities and organizations grow: "Trust comes from a sense of common values and beliefs. When surrounded by people who believe what we believe, we're more comfortable to take risks, experiment, explore."
He gives an example of how we're more likely to trust a 16-year-old with our kids versus an experienced babysitter whom we don't know. "Our very survival," he says, "depends on trusting people who believe what we believe."
With that in mind, when growing a business, it's more important to hire people who share similar beliefs and values versus hiring solely for skill. When there's a disconnect of values, companies fall apart. Sinek calls this moment "the split," and illustrates it with this graph:

Simon Sinek
TEDxMaastricht
Blogger Eric Barker talks about how success is more environmental than we think in his latest post, "Even The Most Talented Workers Depend On Those Around Them." He cites an interview with Harvard Business School Professor Guatam Mukunda:
The unfiltered leader who is an amazing success in one situation will be a catastrophic failure in the other, in almost all cases. It’s way too easy to think, “I’ve always succeeded, I am a success, I am successful because I am a success, because it’s about me, and therefore I will succeed in this new environment.” Wrong.
You were successful because you happened to be in an environment where your biases and predispositions and talents and abilities all happened to align neatly with those things that would produce success in that environment. That doesn’t tell you a whole lot about the next environment down the pike.
Understanding this fundamental truth helps explain why rockstars in some organizations can completely fail in others — for example, why Ron Johnson thrived at Apple and Target, but is struggling to stay above water at JCPenney. Cultivating strong teams and company cultures is a huge challenge, and few get it right.