I have some socks that probably have more darned surface area than original material, just because it amused me.
Socks have a hard life really, and cheap nasty polyester (or significant % blends) ones can last much longer than more expensive pairs. Especially because you won't want to wear them!
I agree that a polyester blend tends to last ages. My Uniqlo 100% cotton socks tend to wear out at the sole and big toe quite quickly (those were rubbish), but my military-issued $1/pair polyester socks last me months, and are comfortable enough for daily use.
Socks have a hard life really, and cheap nasty polyester (or significant % blends) ones can last much longer than more expensive pairs. Especially because you won't want to wear them!