If the used drive is significantly cheaper, e.g. half the price of the same model purchased brand new, I personally would take a chance and buy it. If the used drive is only slightly cheaper, it's not worth taking the risk, given the lack of warranty.
I use a mixture of hard disks, including Western Digital "Purple" drives which are intended for use in video storage systems. I like the Purple drives because they are CMR/PMR and not SMR. I wouldn't be happy without at least four copies of important files.
I keep important photo files on numerous hard drives in four main towercomputers, plus three multi-disk RAID-Z2 TrueNAS Core servers, plus 25GB Bluray, plus 800GB LTO4 tape.
The beauty of Bluray and LTO tape is the media can be write-protected, making it virtually immune from Ransomware attack. Files stored on hard disk (Internal or External) or in the Cloud, could become encrypted if you're very unlucky.
If you do buy the 10TB drive, run a full surface read scan using something like Hard Disk Sentinel Pro. On a hard disk of this capacity, I'd expect the test to take around 20 hours.
Remember, although the hard disk Transfer Rate may start off at 250MB/s on the outermost tracks, the speed will gradually reduce to 125MB/s on the innermost tracks.
You may also find the transfer rate slower than expected when copying thousands of small files in one session, e.g. low res JPGs. If you copy multiple large files, e.g. 50MB RAW images or video files, the average transfer rate will increase.
Slow copying can be a problem when transferring image files to LTO tape from hard disk. My LTO4 drive requires a constant feed rate of 80MB/s. You might think a hard disk capable of up to 250MB/s would cope easily, but too many small JPGs cause my my LTO4 tape drive to pause briefly every few seconds, partially rewinding the tape in what is termed "shoe shining". For this reason I tend to ZIP or RAR smallJPGs before backing up to tape and use a fast NVMe scratch disk.