The question is do you dream or not? If you dream you have no choice you have to believe in it. Well the truth is all inspirational stories are to motivate you. Just that, nothing more. The reality is, for every Jack Ma who dreamt and believed in his dream, there may be millions who did exactly the same but they ended up with nothing. No one tells their stories. So the probability of your dream becoming reality may be one in a million yet that is preached as the gospel truth. But what you do? Don't motivate people?
So the answer to your question is: we are humans, can't stop dreaming, and if can't stop it we better believe in it.
"To dream is human, to make it happen is divine"