That seems improbable. I have bought "merino" socks from Costco and they are only something like 20% merino. I also have Smartwool socks and they are quite different.

I actually like Costco's generic black-and-orange athletic sock as a daily driver. I treat them poorly; we take off our shoes in the house but not socks. As they wear out, I throw them away; once a year I buy a new pack to refresh the losses. I use the Smartwool for activities but otherwise take good care of them. They last.