Psichic vampires are disfuntional beings. As they drain the life force around them, or better, they try to do that, as they are weak in reality.
If one is tough and not fed up with victim/slave mentality, can easily defeat a vampire, banish or spiritually binds them.
Psichic vampires also drain destructive and chaotic energies from people, places, ecc... Some of them also larp around hebrew kabbalah meditations, some even as gentiles. This makes them very disfuntional and dirty, like a big filled up public toilet.
About vampire against vampire.
I don't believe it's a racial matter (in the case of hebrews and gypsies, as they are very evil between their own, and they are very much based on vampirism against their children, especially in judaism), but more simply it's becuase psichic vampires are spiritually like big filled up public toilets, and they aren't good targets with a lot of good energy.
Now, if one as a Zevist needs energy, one shouldn't practice such vampirism crap, but it's way easier than that. Just go under the Sun, and inspire energy from there, then after the meditation, program the energy inside yourself, or donate them to the Gods.
As one becomes more advanced, one can inspire energy from stars, planets, ecc...
Know what are you doing 100% before starting with these, as I said this is more advanced.
To raise energy, there are meditations, yoga, and also the Invocation to Satya (I do this before the Rituals).
You can search more at ToZ for these.
I hope the points are all clear.