Making a backup is definitely a thing in the US.
Drinky is kind of right, but also kind of really reading too much into it, to the point of being abjectly wrong.
All jurisdictions I know of have some concept of a First Sale Doctrine, wherein your "license" to use a copyrighted work comes with, and follows the physical item you purcahsed.
However, in no jurisdiction I am aware of, are your rights curtailed because the item was destroyed. They're only lost if you sell it to someone else. This is for obvious reasons.
A lack of the physical item does not make you guilty of copyright infringement.
It does remove the proof that you didn't commit it, but it's not your duty to prove that you didn't commit a crime. It's the duty of the person alleging you did to prove that you did.
Destructive digitization happens because,
1) storing physical shit is expensive, storing digital shit is cheap
2) and I suspect this is the more important one- if you know you've destroyed the original copy, the license for the copy you made of it can never be transferred away from you.