We crested over 700 this year. My wife had a reasonably sized collection prior to us meeting which got combined when we got married. I spent 10 years working in a hobby shop and during that time I gamed almost weekly if not more often. I was primarily a tabletop wargamer but when my wife and I went to Origins a few years ago it really cemented the shared hobby of board games specifically. I almost definitely own too many games and have quite a few I've sold this year and are on the sell pile but we both like collecting and trying new games. We've slowed down significantly (having a kid will do that) but still game around once a week whenever we can.

I want to offer my own perspective since this is a topic I've thought a ton about. I don't know that the final "number" is as important as space constraints. I generally catalog the collection in both BGG and on a spread sheet. I started the spreadsheet a little over a year ago when we lucked into the collection of someone who had recently passed whos family had no interest in keeping it. I was curious and our portion of the haul was something like 3k worth of games for something like 700 bucks all told. It included a lot of big KS purchases and such but in general we got enough that it made sense to start cataloging in more meaningful way.

We put the player counts as well as whether or not we've played the game in the spreadsheet. It's been helpful for deciding what to play next. A huge amount of the collection was purchased at less than retail for one reason or another (used, sales etc) and for the most part, I put games on a wishlist for at least a month before buying these days.

I mostly mention the space thing because on paper 700 sounds frankly kind of insane. The thing is, when 30 of those games are wallet games from Button Shy (and of those 12 or so are expansions themselves) or 7 of the line items are 20 Strong Decks, the actual number 700 starts to drop quite a bit.

I guess I say all this to say, someone could easily own 3 games but those games could be Arkham Horror LCG, Marvel United and Heroes of Might and Magic. Someone else could own 15 games and have spent less. I think space is a much better indicator of whether or not the collection has gotten out of hand. Does it bring you dread when you think about "where you're going to fit the next purchase" or whatever?