Why would one expect following their dream would correlate in any way to success in life? If anything, given that people think (and dream) alike, it would lead

Why would one expect following their dream would correlate in any way to success in life? If anything, given that people think (and dream) alike, it would lead to supply glut in specific fields. That is probably a part of the explanation of the low salaries in e.g. education, or working with animals. I can think of other reasons, for an average person, to absolutely not in any way try to follow their dream as a source of livelihood; what are the arguments FOR it, though? How did this idea even come about; is it related to the "self esteem" fad in education?