Of course, the power of a quantum computer is capable of a lot, but you also need to take into account the fact that using a quantum computer it is quite possible to crack Bitcoin codes without problems. Repeatedly in specialized media, they say that experts are very active in not only protecting the blockchain, including Bitcoin from a quantum computer, but also to improve cryptography technology through newer technologies. I very much hope that the cryptocurrency, which is now passionate about a significant part of humanity, will not suffer from a quantum computer.
Indeed. A quantum computer can defeat Bitcoin in its current state. With Google's claim of achieving "Quantum Supremacy", the company can take down the entire Bitcoin network in a blink of an eye. But we all know this will never become a reality, as miners will quickly reach consensus in order to protect Bitcoin against Quantum computing attacks. By the time Quantum Computing becomes a real threat to Bitcoin, the pioneer cryptocurrency would've adopted Quantum-resistant mechanisms (Lamport signatures maybe?) to stay relevant within the mainstream world. As of now, the field of Quantum computing is still in its infancy. Slowly but surely the Bitcoin community will explore ways to increase security against Quantum computing attacks, to keep the cryptocurrency going for the foreseeable future.
Considering how active Bitcoin's development team has been over time, I wouldn't worry about Quantum Computers posing a risk to its existence anytime soon. A simple tweak here and there, should make Bitcoin Quantum-ready without hassles. With time, we'll be able to determine if Quantum Computers will be able to live up to the task or not. Hopefully, the field of Quantum Computing would prove to be more beneficial for the growth of the entire Blockchain industry than all the other way around. Just my thoughts