Then it seems your setup is totally fine. If you're upserting 10 million rows a day with lots of columns, then of course you're going to be seeing TB's of disk writes. And remember that SSD's can't even write individual bytes the way HDD's can, they necessarily write a whole page at a time, which might be 4K or 16K, even if you're just updating a single integer.

Your database and SSD are functioning totally normally, as designed.