I heard that sissy hypno is really dangerous. Why is that ?

It is designed to get you subconsciously addicted to gay porn and male effeminate behaviors using hypnotic suggestions and imagery. 

Unless you actually want that to occur, it is potentially very dangerous to your psyche like any addiction, only even less in your conscious control because hypnosis is being used to trigger and control your behavior without your conscious awareness. Someone who is aware of this can take full advantage of it too, not just the porn industry. 

WTF are you talking about?

Mainly because the sites are crammed full of malware, trackers, and ransomware.

The rest of it is just porn.