Easy: could have gotten into BIONICLE as early as 2005, but was lax (and admittedly very young at the time, but that didn't stop me from buying the sets), and didn't get into it until 2008. Didn't care about it until late in that year, and lost interest in the vastly changed story of 2009. Of course, I had huge fan fervor when they shut it down, but no less. Now, instead of having paid 8-10 dollars as a kid for a Toa Hordika or Ignika, I'm paying 40-60 for one.
Especially annoyed about totally missing 2006. I was there for 2005, even if I didn't care, and I was there for 2007, but 2006 is the literal and figurative time slip for my BIONICLE fandom.