Oh, but it does. Innovator's Dilemma.When Microsoft started, IBM could have destroyed them, if they were willing to become a software first and not a Mainframe company. When Google launched, Microsoft Could have easily "crushed" them, IF they were willing to cannibalize their existing business. Facebook/Instagram is one major data point where this didn't happen.

Never forget that "powerful competitors" are slow. Very, very slow, even past 200 employees. Meetings and arguments increase the latency of delivering new products and services. Incentives start to be misaligned that make it difficult to continue delivering at the same quality ( why should I put in 2X to build 100X value, when I'm only getting 0.02%? ) Worry more about the startups that start alongside you.