I find the idea of self-hosting to be really appealing, but at the same time I find it to be incredibly scary. This is not because I lack the technical expertise, but because I have gotten the impression that everyone on the Internet would immediately try to hack into it to make it join their bot net. As a result, I would have to be constantly vigilant against this, yet one of the numerous assailants would only have to succeed once. Dealing with this constant threat seems like it would be frightening enough as a full-time job, but this would only be a hobby project for me.
How do the self-hosters on Lemmy avoid becoming one with the botnet?
Only expose services internally then use a secure VPN to access your services, this makes your network no more vulnerable in practice than not self hosting. If you need/want to expose something to the internet, make sure you setup your network right. Use a DMZ to separate that service and leverage something like CrowdSec along with good passwords, antivirus, and keep things patched.