Fear is a god because it is something that tries to control you. So is self doubt (if you believe you can't do something no one can make you) & confidence (if you believe you can you will). No one but yourself can take away either. You can not teach someone (e.g. you can show & someone how to do something, but you can't make them do it), you can only guide them.

So are greed & lust

I agree. Fear is the mind-killer (Bene-Gesserit axiom). And as for having no confidence, well then you can't rely upon yourself, which weakens you.