HDMI is made mainly of copper, which makes it cheaper.
In addition, the technology boasts various advantages such as high bandwidth and compatibility with most devices.
Copper is a cheaper material but is more susceptible to interference. On the other hand, optical fibers are more expensive, but they use light to transmit signals, making them less likely to suffer from interference.
Optical cables retain sound quality even at 10 meters. But if you’re going to use HDMI for your sound system, it would be best to keep it under 5 meters to maintain sound quality and low latency.