Let’s compare the electron-based Minecraft launcher with Minecraft itself.
The download is 400MB vs 11MB (+the 60MB JVM runtime)
The RAM usage is 300-600MB vs. 256MB
I mean, I don’t see how electron comes out ahead in this (and it only runs the damn launcher, not the actual game).
Java definitely is the least of your worries. And with JavaFX you can even use the web APIs for UI.