Pseudoscience can be a dangerous thing, especially to an audience that doesn't know better. The danger of pseudoscience resides within its seemingly scientific background when it, in actuality, contains no scientific evidence. However, because of this seemingly scientific research people are willing to trust it with something as huge as how to live their lives. A perfect example of this is astrology.
The definition of astrology, as stated by the free online dictionary, is, "The study of the positions and aspects of celestial bodies in the belief that they have an influence on the course of natural earthly occurrences and human affairs." In common tongue astrology claims that the positions of stars and other objects in space determine what is going to happen on Earth. Astrology claims things as even as specific as telling people to not think too hard today or that accidents are likely to happen today (claims from astrology.com). This is dangerous because it's human nature to believe things like this.
Because we are naturally looking for order where there isn't any we can fall prey to many claims and ideas, especially those that "pretend" to have scientific backgrounds. When we read a horoscope that says, "Things have been stressful lately. It's time for you to relax and not worry about everything," we immediately think of the stresses we've faced recently and think to ourselves, "You know, I have been stressed lately. I'm going to stop worrying." Now although there is probably no danger in reducing your worries, you've done it because something with absolutely no real reason has told you to. Another danger comes into play when one gets comfortable listening to pseudoscience claims and now suddenly someone is changing his/her life due to falsehoods. This is a start of a scary process.