Thanks to this question, I now understand the existence of the "Wi-Fi" process running in the background on my mac.
But why does it require 500+ MB of RAM when neither the menu item nor any dialogues are open?
When I quit it using activity monitor, it reappears and only uses 8 MB for a while. But after a couple hours, it is back to using more RAM than Google Chrome.
I am running macOS 10.14 on an early 2015 macBook pro.