How to tell someone to not host a minecraft server them self?

He does not know a lot about computers. He is saying he knows what he is doing when he does not. He does not even know how to clean install windows. I own my own server because i have checked it off with my ISP and also I have a server pc. I know how to port forward. I install the latest security. I know how to deal with DDOS attacks. I know how to all of that. He does not even even think anti viruses are needed Computers. I exampled to him he should pay for one instead and he is ignoring me. And called me a lier. What should i do