From what I've been seeing, a lot of people hate and fear psychic vampires, because they believe that one might attack you. Why? Psychic vampires don't just feed from human energy.
I have never seen someone fear a psychic vampire because they believe one might attack them. Most Occultists would have these potential to harm anyway. So it does not make sense to fear them in such a manner.
Rather , I believe they are scorned is because they are so tiring to be around. A unconsious one anyway. A unconsious one are like leeches , sucking away like a greedy sponge. I don't even know how on earth did they get to such a habit. They can be such a bore and dull to be around.
A consious one , aware of their so called "Defiecency" is even worse in my opinion. Even if they do not target other human beings , they can be rather "needy". I personally don't believe that their energetic field is damaged thus that happens. I am rather of the opinion that it is more of the lines of an addiction. They get a kick out of it , unconsiously or not.
And even if it were damaged , which I highly doubt , a fair amount of it is in the mindstate. Such self-destructive thoughts continues the cycle. And thus , the circle begins itslef anew. If one were skilled enough that they learn how to draw energy from the earth , the surroundings , the planes to support this little "kick" of theirs, they can also research so that they are able to work out their own problems.
(This are just my opinion and beliefs as of this moment. Remeber , opinions and beliefs! It may or may not be true. That is a nature of a opinion!)