It's been a humor among most speculators and might still be theoretical, taking many years before it happens, if it ever does.
Sometimes, to avoid headaches, I choose not to think about what might occur in the future.
As of now, there's no need to panic. There's no known quantum computer today that can break Bitcoin private keys.
Don't dwell too much on the future, as we don't even know if we will still be alive when quantum computers are discovered.
Remember that Bitcoin’s security based on a cryptographic method known as the Elliptic Curve Digital Signature Algorithm.
Thus, breaking a Bitcoin private key requires solving a very difficult mathematical problem.
As long as you own your private key and never expose it, you're safe.
As the quantum computers are trying to be a threat to Bitcoin,the Bitcoin developers will not just watch, they will also be making researches on how to profer solution before that time, because if it happens it will be disastrous to the Bitcoin community which I know they will not want that to happen after achieving their aim and goals, therefore an alternative will be out to solve that problem.
But for now all you have to do is to store and save your coins in a well secured wallet using Electrum and proper backing up of your seed phrase and not exposing your private keys to any one
The Bitcoin developers are working seriously to tighten the security around the network to avoid things like quantum computers attack from happening, in as much as the security of Bitcoin is paramount to them and everyone .