> it won't be a big deal.

This isn't a space I know too much about, but even if we all start using quantum-safe encryption for everything today, won't the arrival of quantum computers that can break traditional encryption not still be a big deal?

Given that intelligence agencies, tech companies and various bad actors have been storing encrypted data for a long time, hoping to decrypt when (if?) that day comes?

Intelligence agencies and companies for which industrial espionage is an actual concern will re-encrypt their data storage, or have already done so. The only risk is on data that was already obtained with a vulnerable encryption. So there is some risk that a few secrets are lost, but it won’t be everything. And if you were to start now and quantum decryption isn’t viable for a decade then any secrets that do get exposed are surely less of a problem than if they were discovered today.

Definitely, but then the damage is limited to the encrypted data that those actors managed to intercept some years before. Compared to QC arriving to an unprepared world, that's a very limited impact.