Here is sharing my opinion :-
Being a student of psychology, I assume you'd soon learn how to conduct a research to answer question "why do people do the things they do", in this case, "why do people have the perception that psychology enable people to read minds".....

But... wait... you're not here to ask sincere questions.

1, I'm pretty sure you don't ALWAYS get the question. You might get once or twice and confirmation bias makes you exaggerated the occurrence of such incidence. ...

2, you don't want to know the answer of "why people believe in stupid things", you want us to tell you "because people are stupid", more specifically, "people are stupider than YOU".

So in reality, this question is not an sincere question hoping to understand human behavior, it is a condescending, self-congratulatory, arrogant rant...

Oh, and, have you ever thought about people are just joking with you? No? Are you sure you want to study psychology? you seems rather lacking in compassion, which is needed to be a good therapist to help people; or objectivity, which is needed to be a good researcher....