Blockchain itself is secure, but poor implementation can create risks. Bugs in smart contracts, phishing attacks, private key theft, and unverified apps are major threats. Solutions include auditing smart contracts, using multi-signature wallets, never sharing private keys, and educating users. Developers should write secure, testable code and users should use trusted tools.

Example Shown in Video: The DAO hack in 2016 occurred due to a smart contract vulnerability and resulted in Ethereum’s first major fork to recover stolen funds.