Avoiding crypto hacks involves a combination of personal security measures and broader systemic safeguards. Here are key strategies:

Personal Security Measures

1. **Use Hardware Wallets**: Store your crypto in hardware wallets like Ledger or Trezor, which are offline and less susceptible to hacking.

2. **Enable 2FA**: Use two-factor authentication on all accounts related to your crypto assets.

3. **Be Wary of Phishing**: Avoid clicking on links from unknown sources and ensure websites are legitimate before entering credentials.

4. **Regular Software Updates**: Keep your wallet software, operating system, and antivirus programs up to date.

Systemic Safeguards

1. **Blockchain Monitoring**: Services like CipherTrace and Chainalysis monitor blockchain transactions to detect and flag suspicious activities.

2. **Smart Contract Audits**: Ensure smart contracts are audited by reputable firms to detect vulnerabilities before deployment.

3. **Multi-Signature Wallets**: Use wallets that require multiple private keys to authorize a transaction, reducing the risk of unauthorized withdrawals.

Flagging and Prohibiting Hacker Wallets

1. **Blacklist Mechanisms**: Some exchanges and services maintain blacklists of addresses associated with illegal activities. These addresses are flagged, and transactions involving them are scrutinized or blocked.

2. **Regulatory Compliance**: Regulatory bodies can impose rules requiring exchanges to freeze assets linked to flagged addresses.

3. **Decentralized Solutions**: Protocols like "watchtowers" in the Lightning Network monitor and react to suspicious transactions. However, these are less common and harder to implement on a larger scale.

Challenges

- **Anonymity and Decentralization**: The inherent anonymity and decentralized nature of cryptocurrencies make it challenging to enforce these measures universally.

- **Cross-Jurisdictional Issues**: Different countries have varying regulations and levels of enforcement, complicating a unified approach.

By combining robust personal security practices with systemic monitoring.