A lot of knitters and crocheters have a stash of yarn for future projects saved in their homes. Unfortunately, much of it is possibly 100% acrylic.
I know acrylic is durable, can be soft, and comes in millions of colors and weights. However it does not work as well for cold and wet weather like natural fibers. Acrylic clothing will hold in heat, since plastic is an insulator, but it does not breathe well and will leave you cold and damp after the clothing is full of sweat. Wool and Alpaca are both great insulators that “breathe” and wool is known for keeping warm even when soaking wet. (Wool is also naturally flame resistant!)
I’m not saying throw out all your acrylic yarn, but if that is all you have I’d recommend sorting through it and selling your least favorite of the bunch. With the money from selling your old yarn buy some wool or alpaca yarn (or un-spun fiber if you spin). It doesn’t have to be 100% wool, 50% or 25% is fine too. Your acrylic yarn you have left can be doubled up with your wool/alpaca yarn giving your items strength and durability from the acrylic and the warmth, breath-ability, and fire-retardance of wool. Items like socks, gloves & mittens, elbows on sleeves, and knees of pant-legs can really benefit from being reinforced this way.