Is it possible that all current blockchain-based cryptocurrencies (like Bitcoin) can be hacked in just a matter of seconds? It indeed seems possible, based on the statements made by Dr. Joseph Liu, Associate Professor at Monash University.
Dr. Lius qualifications add allot of weight to his statements. He is the Head Researcher at Monash Blockchain Research Lab, the Chief Scientist of HCash and he is also the co-creator of the Moreno cryptocurrency. In other words, his statements about cryptocurrency development should be taken seriously...
At the moment I don't think it's possible anyone has the enablement to hack all wallets. Except if there is a kind of keylogger on one's PC to create access for the hacker. Otherwise every other wallets would've been hacked by now. Hackers don't spare wallets with funds, even if it's a tiny amount. This is why we should be very careful with our passwords/private keys/passphrases. Guard them well with all diligence, away from the preying eyes of scammers and hackers.