What Is the Network Effect in Crypto?

The network effect is the reason a crypto network gets more useful as more people use it. One person with a wallet has nothing to do. A million people with wallets have a market, and the millionth arrival makes the network slightly better for everyone already there.
The phone in your pocket
The first telephone ever built was worthless. The second one made a call possible. The value came from who else was reachable, not from the device itself. Money behaves the same way: a currency is useful when other people accept it. That is why a technically better coin can lose to a worse one that everybody already holds.
Where you see it in crypto
Bitcoin is the most recognised name, so it is the one exchanges list first and the one companies buy when they want exposure. Ethereum attracted developers, the developers built apps, and the apps pulled in users who then wanted more apps. Tether is accepted nearly everywhere because it is accepted nearly everywhere. On Uniswap the effect shows up in the price itself: the more money sits in a pool, a shared pot of two tokens that people trade against, the less the price moves against a large order, so large traders go there, which makes the pool bigger still.
Why new chains have it hard
A new blockchain can be faster and cheaper and still sit empty, because the wallets, the exchanges, the security audits and the users are all somewhere else. Solana got past that by being cheap and quick for long enough that apps moved across and brought their users with them. Most attempts never do. So when you hear about an "Ethereum killer", the useful question is not whether the technology is better but whether anyone has actually moved.
The limit of the idea
Network effects lock things in, including mistakes. Busy chains get congested and fees rise exactly when demand is highest, and people put up with it because leaving means leaving everyone else behind. Treat "everybody uses it" as evidence of staying power rather than of quality. Next, read what decentralization actually means or why crypto matters.