A new third party SSD you buy today has a typical lifetime above 500 Terabytes written, and often as high as 1200 Terabytes written.
Users simply are not generally running into those maximum limits, and even when they do, a typical drive exceeds them by a large amount.
I would not worry about that previous use. Just enjoy your Mac.
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It is now and has always been Best Practice to make a backup of your files. Apple provides free Time Machine software, built onto MacOS, that can update your backups automatically at low priority in the background. In most cases, it runs without disturbing your important work at all. When you need it, your Time Machine backup is likely to be there, and likely to be very recent.
All you need to add is an external drive to hold the backups, and it does not even benefit from being FAST.