Don't miss the point
Your encrypted data is stolen today including the key exchange bits. Don't be smug.
If your data has a lifespan longer than 10 years (say, the names of all the spies and moles in <name your country>, or your GDPR protected data where your company is bankrupted by the brusselcrats when the data is revealed, or your carefully constructed pile-o-shell companies for tax evasion) you are exposed when that quantum computer pops into existence. Yes, I know, the inflexion isn't like that but you get the drift. And it could be never, or 10 years from now, or 2 years from now, or 2 years ago that a suitable QC exists to crack vulnerable encryption.
The data has to be resistant to quantum attack n years before a QC attack is feasible, where n is the time value of the data.
Better hope that QC are further than 10 years away, because it will take longer than that to modify the infrastructure to be quantum resistant... on the other hand, it is a brave new world for stealing valuable resources. The number of vulnerable points is truly astonishing, QC as the supernal zero-day.