I am very interested to know if cryptocurrency wallets like Bitcoin Core, NEON, Electrum can ever be hacked ?
definitely yes, but it is because of the users end not because the of the wallet perse especially if your wallet is decentralize, hacker entry is throough emailed phising site, or crack app downloads with malware, or visiting suspicious websites etc. so you you to be very carefull.
anything can be break doesn't matter how strong your security is. We should not share our passwords with any one plus we have to use strong passwords because anyone can guess it.