I am very interested to know if cryptocurrency wallets like Bitcoin Core, NEON, Electrum can ever be hacked ?
Yes they can hack your wallet. Just don't share your private key and Password save it to yourself and if you don't know how to secure and process your coins, you may ask to a person you trusted most so they can guide you so you can learn to yourself.
In my own opinion, the only way for you to get hacked is to unintentionally reveal your self by logging on phishing sites but there is other reason for you to get hacked if you are always careful.