Primarily network effects. Uniswap v2 was cloned by Sushi (and many others), with the difference being that they offered a token to their users for migrating li

Primarily network effects. Uniswap v2 was cloned by Sushi (and many others), with the difference being that they offered a token to their users for migrating liquidity over from Uni. It worked, at first, until Uni responded in kind and airdropped a token to their user base, which helped them to retain loyalty. But the two have since diverged in product depth and breadth with Uniswap taking a deeper AMM approach (with concentrated liquidity) and Sushi becoming a broader AMM available on multiple blockchains. That is to say, that even if a fork occurs, if the product is sufficiently complex, it's going to need improvements and users are going to stick with the contracts with the deepest assurances via reputation. With AMMs in particular, liquidity is a big factor. It would be tough to enter the Ethereum AMM game now without something novel to add, as you would struggle to attract liquidity otherwise. Liquidity begets liquidity.