I use litz wire for headphone cables. For a cable that's constantly on you, there's always some chance something happens unexpectedly. I've broken my share of earpods.
Litz wire doesn't increase the durability as such, merely reduces skin effect in RF applications. Sennheiser used to sell steel cables for their professional headphones. Now those are durable. I ran over mine with my chair about 50 times a day and the cable was still going after 10 years.
Steel makes sense for extreme durability - I suppose you could use extremely thin steel wire for in-ears to make it flexible, though it might require a very special alloy to be thin and low resistance?
In my experience, litz wire is exceptionally flexible and suitable for getting shoved in a pocket frequently. Each wire can be quite thick due to the flexibility.
