Though I am no psychologist, here’s a simple but plausible explanation as to why The Dream is so common.
While we still don’t know why dreams occur, dreams are reflections of our own personal memories and experiences. Since BIONICLE, and more specifically finding sets in stores, is/was a large part of our lives, it makes sense that we would eventually dream about it. Similar to some adults will still dream about being back in school, or dream about people you haven’t seen in ages.
As for my own personal experience with The Dream…
^^^^ This ^^^
Whenever I have The Dream, it’s always in some weird place you wouldn’t expect, like a bookstore or an old thrift shop in the middle of nowhere. Rows of classic G1 sets in mint condition. Pick up a box only to find it’s actually “Galaxy Warrior”, “Robot Hero” or some other generic bootleg name.
Every. Single. Time.
Even in my dreams, I can’t win.