parasites are more likely to go after those with a “weak” state of mind but everyone is subject to parasites. Of course there are ways around this be it shielding the mind from astral thoughtforms to learning to shield yourself from actual entities with malicious intentions towards you.
When it comes to the astral/mental plane it’s in my opinion better to ward off a little space in the astral for your practices before exploring the rest of it, keeping in mind it’s a place literally warped by the minds/imaginations of humans and nonhumans not just us here.
Now I can’t really agree with the use of the term evil because that’s not the case, parasites are just thoughtforms who become primal in a way they are simply needing attention so they do not cease to exist, or ‘real’ entities who aren’t doing it out of “I want to be evil” but rather doing it out of some desperate need for power.
but drug abuse can lead to issues with such but there’s also some possible underlying issues prior to that.