Playing devil's advocate here, but the service fee (at least to my mind) is more for the maintenance & upkeep of the infra.
I'd gladly move to self-hosting if it was only me. But after a few months, I was able to convince my wife to use it for convenience and security. So if there's an issue with the self-hosted version, it wouldn't just be me impacted, but my wife. And that's an SLA you don't wanna break. :D
Also, while I know I could probably do a decent job securing the hosting server, I would rather not have that on my mind. That's not my day-job, so I'll leave it to a team of people who are paid to do that.
Lastly, the service fee is $60/yr, but for sake of argument, lets call it $100. That's 2hrs of my time at my hourly pay. If setting up a self-hosted version takes me more than 2hrs to get it running, it's not worth my time.