Making great audio cables is much more than wrangling up ready available wire, terminations, wrappings. Both the materials used AND wire weave geometry make huge differences.
Understanding Audio Cables - construction, electrical properties, cost:
Galen Gareis, a (now retired) product development engineer at cable manufacturer Belden, created Iconoclast cables from scratch with the backing of Belden. I've found that the white papers from Iconoclast are especially helpful in understanding design goals and why some cables are so expensive.
https://www.iconoclastcable.com/story/further white papers:
RCA/XLR design brief:
https://www.iconoclastcable.com/story/rcaxlr.pdf
Speaker design brief:
https://www.iconoclastcable.com/story/speaker.pdfSure, you can make your own cables to connect your components and it'll work of course, but moving up the audiophile cable chain should/will result in better audio quality. Also, the more transparent your system and/or the better your critical listening skills, the more you'll notice/hear the differences. Whether the price/performance is worth it is subjective, often a topic of heated debates.