Sui chose Move instead of Solidity because Move’s resource model, ownership semantics, and safety guarantees align perfectly with Sui’s object-based architecture and parallel execution engine. Solidity simply wasn’t built for that.

You use Move instead of Solidity on Sui because Move is designed with assets and safety in mind. In Solidity, tokens and assets are just numbers in a contract’s storage, which means a bug like re-entrancy or a missing check can easily cause losses. Move, on the other hand, treats assets as first-class resources with strict ownership rules: they can’t be copied, accidentally dropped, or transferred without permission. This means you don’t have to manually defend against common bugs like double-spending or dangling references—the language prevents them at the type level.

For example, in Solidity you might just update a balance mapping:

mapping(address => uint) balances;

function transfer(address to, uint amount) public {
    require(balances[msg.sender] >= amount, "Not enough balance");
    balances[msg.sender] -= amount;
    balances[to] += amount;
}

In Move, you model the token as a resource, so it can’t be duplicated:

struct Coin has key {
    id: UID,
    value: u64,
}

public entry fun transfer(coin: Coin, recipient: address) {
    transfer::transfer(coin, recipient); // ownership moves, no double spend
}

This ownership model makes reasoning about assets much clearer and enforces security at compile time rather than relying on runtime checks. If you’re building financial apps, games, or NFTs, Move gives you built-in guarantees that reduce the attack surface compared to Solidity.