Several reasons, I like to try make stuff, abelit badly in some cases 🙂
I don't have a midi cable, but i do have some vintage DIN/midi plugs in a box, a barrel jack socket and a bit shielded pair ... [ in a previous life, and with no previous knowledge, tools or internet, I reclaimed and rewired 120pin EDAC cables into interlinks for my mobile studio, from that I learned that one does not pick up a soldering iron and simply walk into mordor]
Sauron's Multiplug
Yeah, I could just buy the things pre-made from ebay, but where is the fun in that? And when I have f**ked it all up, and failed, but learned a few things then I will go to fleabay 🙂