Within the Collector Forums universe . . .
Short answer: One who has 50 or more posts on the Forums.
Longer (and more general) answer: One who has an enduring interest in and affection for, perhaps even addiction to, lighthouses in general and Harbour Lights collecting in particular.
If you do a search on "Wacko" in these Forums, I know you'll find many longer, more elegant definitions, and many discussions on the topic.
Welcome aboard, binky52. Only 48 to go!