You can compile in only the used stuff with various build flags, not sure if they did that though. I've done that before to make a pared down SDL that only does audio playback.
We're holding pretty steady at $3400-ish / month on open bowling alone. No leagues yet, no snack bar yet, no beer yet. It's not FAANG income by any stretch, but it's doing -so- much better than I initially expected!