Yeah, one could make a similar argument with self-hosting: How the data is transferred physically through undersea optical cables, how internet routing works and the complexity of it down to how the hardware underlying his Nextcloud installation works. It is really a miracle that it all works, though.

I've been self-hosting my e-mail, and I'm thinking of switching to Google Apps, Fastmail or Protonmail due to the fact that sometimes my emails just go directly to spam. There's also the worry that my server might get hacked, and the maintenance that you often have to do. My time is orders of magnitude more than the few dollars a month all this costs.