All I know is that after being threatened by a ransomware fraud, I now am backing up my data files to RW/DVD. I have also got a couple of external reader/burners in addition to the ones in my computers.
Haunt rummage sale computer departments, buy drives and disks.
I use flash drives but do not totally trust them for the reasons mentioned and linked above.
The cloud is subject to the same laws as everything else, with the additional factor of being vulnerable to attack.
Entropy sucks but is a law of nature, like gravity.