Collectamitus

A friend asked me how he might search about people who are “collectors”, and what makes them tick. Here’s the start I gave him: combine “collectors” and/or
“collecting” with psychology signwords like “psychology”,
“compulsion”, “addiction”, or “behavior”.

Here are a few interesting links I found on some quick searches (some stray into humor, “abnormal” collecting, and compulsive consumerism):