If everyone stops writing game engines then who is going to program unreal engine/unity/godot?
The people working for Unreal/Unity/Godot. Nobody writes search engines any more - except for Google et al. Nobody writes advertising systems - except for all the advertising businesses.
I’ll admit I lost the plot a long time ago, but there’s a part of me that wonders if the main purpose behind the game engine and graphics card treadmill is to line the pockets of people who sell games engines and graphics cards. My subjective sense of the connection between technology and enjoyment as a player started to degrade about a decade back.