No, you are just full of ****. MSE is free, it does it's job well, and everyone is going to laugh when you get a virus and don't notice till it's too late because you forgot to get any defense.
Whether you need it or not having having it at all just incase is better the needing and looking like a dumbass when you don't have it. Think of it like a flu shot, sure you won't need if it your careful, but it doesn't cost much(or in MSE's case anything at all) and it's one thing to worry a bit less about.
I was using it for a year until I got fed up with how bad it actually is compared to Avast.
Just get Avast, that's all you need alongside Adblock.
On that note, DO NOT use any of the "optimizations" AVG tries to get you to use, free or not. They will destroy your computer, more or less. Just don't do it, if anything just use free AVG, update and set your settings, and leave it be. I still recommend that you uninstall it and get Avast.