When buying secondhand clothing you don't always get to choose the raw materials you encounter. Rather than discarding pieces made from leather, wool and other animal materials (that would inevitably end up in a landfill), it makes sense to give them a second life without supporting the companies that profit from animal cruelty by producing them in the first place.

As an example: on one hand, the most common and most affordable faux leather options made today aren't biodegradable. They're made from synthetic fibers that can take over 500 years to break down completely and, as a finished garment, they usually don’t last nearly as long as a well maintained real leather piece (usually lasting around 5 years on average, compared to something that can last for generations if it’s cared for). On the other hand, buying brand new animal-based materials for aesthetic purposes is cruel and absolutely unnecessary for the suffering it causes. However, if someone were to pass one down to you, it would likely last a lifetime and keep you from having to repurchase a faux version every few years, which would inevitably end up in landfills each time. Sourcing and wearing secondhand pieces that already exist in the world and extending their lifespan, regardless of material, seems to be the least damaging alternative rather than looking at pieces from either of these options as something disposable.

I urge you to think consciously and draw your own conclusions about what we choose to purchase and wear, and how that is an intersectional issue between factors such as sustainability (secondhand vs new), animal welfare (animal based vs synthetic), human welfare (fast-fashion vs slow-fashion) among many others. And of course, consider how comfortable you feel with any of the options available to you, depending on accessibility, affordability, personal views, etc.