They aren't dangerous if you dont take too much. If you have a negative interpretation of the experience it can scare you and make you feel crazy or like you'll be stuck, but you simply wont. The first time I ate shrooms I took 3.5 grams all at once and was tripping so hard that at the peak I couldn't recognize my personality/felt seperated from myself and pretty crazy(I now interpret this as ego death or seperation from the ego and find it quite therapeutic and sacred), I was in a place with some people I didnt trust and that manifested itself in faces of people turning evil, ect. This is what i would consider a psycho-mimetic trip, though I do not think I have any psychotic issues, one must respect the medicine and try to understand the nature of mind manifesting drugs if they want to use it in a positive way. I have had 0 lasting negative effects from psychedelics. (dmt once, shrooms 9 times, acid once) Now I dont ever trip around people I dont trust or in a unsafe setting, and have never had a bad experience again. Getting started with psychedelics, always take it slow, I recommend a gram to start with and garantee no negative lasting side effects.
You must always take into account peoples mental states and that some people probably aren't going to receive a psychedelic experience well.