>Most flash has average wear out after 300k cycles

No it doesn't. Most 1TB drives are rated for around 600 TBW, so enough to overwrite the drive 600 times, nowhere near 300k cycles. If you search for specs of NAND chips used in SSDs, you'll find they're rated for cycles on the order of hundreds to thousands, still nowhere near "300k".

https://www.techpowerup.com/ssd-specs/crucial-mx500-4-tb.d95...

12GB a day isn't very much. If your working set is larger than the 8GB RAM, you're swapping multiple times per second. It doesn't take very many megabytes per swap to reach 12GB if you're doing that multiple times per second.

that doesn't maths