MacBook Pro SSD - Very High Wear_Leveling_Count Value?
I don't know either how exactly to interpret the RAW_VALUE column (the big number in the final column of the line starting with "173 Wear_Leveling_Count"), but the most significant values in that line are columns VALUE and THRESH. 

As long as VALUE stays well above THRESH, your disk should not be approaching its specified end of life yet. I believe the initial value on a fresh disk is 200. When it hits 100 (my value for THRESH), it will have performed as many erase cycles as guaranteed by the manufacturer. After that you're running on borrowed time. On my (relatively lightly used) MacBook Pro, VALUE is 0197, meaning I am perhaps 3% into the life of the drive. 

For what it's worth, my RAW_VALUE is 12,891,062,312, a little lower than your value of 12,895,125,514 and about 1/1000 of 12,567,284,681,697 (VALUE: 093) and 13,031,154,781,293 (VALUE: 87) reported in one of the other answers. 

For information, the file system seems have written 5.4 TB on my machine so far:

175 Host_Writes_MiB         0x0022   099   099   000    Old_age   Always       -       5445917

What matters for the actual life of the drive is not the data logically written by the file system but the actual internal write cycles, which can be significantly different. However, if what I have written so far is about 1/30 of its lifetime limit, that would be about 160 TB which sounds about right for a 256 GB drive like mine.