Its just an upgrade to 4G though. They remove 4G networks and add 5G, if your phone only support 4G you stay on the 4G frequencies.

It allows for better reception, faster speeds, lower ping, more users.

The tech is straight up better in any scenario and in many places it has already replaced 4G. But any 4G device is compatible with 5G networks so users won't know if they are on 5G or not :)