Yes, a lot of people did take this seriously. The 'predictions" were posted all over one of the dorms at my university, and a number of profs who are known skeptics were confronted in class by students with the fake predictions.
It may be hard to believe that people would believe this stuff -- but how about all the people on this board who seem to think that there really was the face of Satan in the cloud of smoke from the WTC fire.
It is not closed minded to state unequivocally that this stuff is bunk. Clouds make patterns. We sometimes make those patterns into something recognizable. We all did that as kids. We still do it, but that doesn't mean there is any real meaning t the pattern. And regarding Nostradamus' "real" predictions. They are all vague, often mistranslated, and they only ever seem to fit events AFTER THE EVENTS HAVE OCCURRED. They never truly predict anything. Our ability to make it seem as if they predicted what happened is the well-known phenomenon call "retrofitting." The correspondence between what Nostra wrote and what has actually happened is all in our minds.
A well-known saying -- it is good to be open-minded, but not so open-minded that your brains fall out
