And to add to Robert’s already detailed reply, you’ll also need to take care troubleshooting your Discourse instance and getting support from the community. Search, #support and #installation are very useful for this.
But if you follow the official install guide, you know your way around a server and are a seasoned Discourse user, then self-hosting is a very good option.
I’ve had a frightening number of people do absolutely nothing and not come back to me for years after I’ve done an installation wanting an upgrade. I don’t recommend that.
If you push backups to S3 and have that configuration in your yml file, then the yml file is all you need to recover from a catastrophy.
Mostly you can do upgrades from the web interface, but about 3x/year you need to do a command line upgrade, which is usually as simple as ./launcher rebuild app. Sometimes, it’s a bit more complicated. I offer a service where I do those upgrades when they are required, but I suspect you don’t need that.