Sorry. Indeed that’s true. In fact, I have worked with someone who did, in fact, manage to lose control of their Amazon account and they lost their stuff that was on s3.
No one has ever been sorry to have too many backups (unless, perhaps, they were paying for hundreds of extra copies–I once paid a bunch for egress fees because I had the download s3 to local setting turned on for bsky.app).
There are plenty of ways to sync s3 to a local hard drive. S3cmd is one that I use