[lee]

it depends... polymers (synthetic) would probably last "longer" simply because its a continuous thread of plastic as opposed to natural fibers which are fibers (usually cotton) that are wounded to make thread. and high-end designer garments tend to fall apart due to 2 probable reasons:

1. high-end garments are generally hand-made/hand-finished (either due to construction that is only possible by hand, or the whims of the designer to construct with hand), which risks human error and inconsistency, which is also the reason u r paying more for it. there may be more attention to detail but that also means its generally more fragile because its not machine-made

2. high-end garments don't have the economies of scale of mass manufactured garments have so thats also why they are more expensive.. not so much because of their high construction cost.