Network effects are a very defensive competitive advantage. Was easy for Facebook to copy Snapchat's features but its another thing to change behavior of millions of consumers
Some of the strongest network effects in tech
What are some other companies with very strong network effects that provide a defensible, competive advantage?
$TSLA! As more Teslas hit the road all Tesla drivers benefit as the company collects driving data that's used to refine the cars' features and skills. Plus the addition of superchargers which make charging more accessible and available.
An obvious but important one is $AAPL . One example feature that Apple invests in is the App Store. Since there is a large market population there is more value for app developers to invest and concentrate on IOS apps. A greater number of developers mean statistically better made apps and more variety, which increases the value of owning an IOS device to be able to use these apps.