When Satoshi Nakamoto launched Bitcoin, the first cryptocurrency, the developers and early investors were highly optimistic because they had found a way of countering distrust from centralized entities and intermediaries.
The design with highly sophisticated encryption, decentralized structure, and irreversible transactions was expected to make the system inviolable and unhackable.
However, things do not appear to follow these expectations. The system has become vulnerable to high tech criminals and even human error.
CoinCheckup published an interesting guide you may want to read:
https://howto.coincheckup.com/cryptocurrency-security/