You are right, today, most of the crypto-burg is centralized. They have a single “brain” that makes decisions and stores user data. This situation presents many threats. In particular, hacker attacks. Traditional trading platforms store private user keys in a centralized repository. And digital attackers are finding more and more loopholes to get to these keys. As a result, the number of thefts of users cryptocurrency is steadily increasing.
Coincheck is the latest example. In early 2018, hackers found a breach in its protection systems and took more than $ 500 million from users accounts. Although the exchange promised to repair the damage and increase security, no one will give 100% guarantee that this will not happen again.
Decentralized exchanges easily fix this problem. They do not take in storage neither cryptocurrency, nor private keys of users. Most of the DEX works on the principle of Matching. In fact, they are only “pimps” - they find a buyer and a seller, who make a deal from their own personal wallets. And since the cryptocurrency or the keys to it are stored by each individual user, hacker attacks become simply unprofitable.
The exchange itself takes place, for example, with the help of a smart contract Ethereum. This ensures transparency and security. According to this principle, in particular, the crypto-exchange 0x will work, where there will be no commission for the auction. At traditional sites, the fee can reach 1% of the transaction volume. Not to mention the commissions for the withdrawal of cryptocurrency.
Of course, hackers can hack and dex. But since all transactions are recorded on the blockchain, attackers will have to gain control of 51% of the network before they can steal the cryptocurrency.