What's the point of light entering copper and retreating?

The commercial technology of optical fiber has matured, and the cost has been greatly reduced, which has obvious price advantage compared with copper cable. In terms of implementation technology, optical fiber has high bandwidth (so-called high speed), long transmission distance, anti-electromagnetic interference and flexible networking (there is no need for active relay equipment in the middle of existing pon networks; And can directly go to the user's home to achieve full-service supply, such as TV, telephone, Internet, Internet of Things and so on. ), these characteristics are beyond the reach of copper cable.