Even cheap fabric 'home made' kilts can last longer than might be expected if they can be remade to hide any damage or stain or fading - assuming that the owner wants to hide it.

I have several kilts which are made from fabric which would have been worn out long ago if made into conventional garments. The kilts have been remade as I have shrunk, and that has hidden fading and stains, and I have even been able to cut out damaged pleats during adjustment.

Wool can be very long lasting - I have a couple of knitted items I made some thirty to fourty years ago and they are still good. As long as the moths or other chewing insects don't get it wool can last a very long time.