By now, most people are aware that electronic equipment shouldn't be through in the trash. Metals inside the equipment can become hazardous waste, leaking particles into landfills and possibly into the groundwater, not to mention never degrading at all. Cables and cords are a different matter, though. Not as many people realize that these simple fixtures have to be treated as e-waste or e-recycling, too. Cords, cables, lines, whatever you have, usually has an insulating layer of plastic or rubber covering metal wires. These simple parts are not good for landfills or even home recycling bins.
The metal in the cords, be it copper or aluminum, can leach out. That pollutes the soil and water if groundwater supplies are close to the surface.
Tangled Masses and Loss of Space
You might have stored the cables neatly, but as they move from place to place, they're going to get tangled up and eventually form a mass that traps other items. If you place the cords into the regular recycling bin at your home, you risk making a mess that recycling workers can't easily deal with. These cables need to go specifically to an electronic recycler, not your home recycling company.
These cables themselves are not going to spontaneously combust. But if they are exposed to flames, such as in a landfill that's caught on fire (in a bushfire-prone area, this isn't so far-fetched) or in a trash pile that someone is trying to secretly burn, the metals and insulation could produce dangerous fumes. The e-waste or recycling center can store these, so they are protected from potential flames.
These cables and cords aren't necessarily trash that will be sent to special waste deposit areas. Those metal wires can be melted down and reused, or if they're copper, they can be sold for scrap (it's inadvisable to try to remove copper wiring yourself as this is time-consuming and possibly dangerous since it requires constant use of a scraper or knife). An electronic recycling company is the best place to take cables in good condition.
E-waste and recycling events are held regularly in a lot of cities, and if you can't find events, you can look companies up online and take the goods to them. Don't let these simple items create a huge mess. Take them to an electronics recycling or disposal center that specifically handles electronic waste