With a collection this big (and trust me, it seems only to expand) it's useful to find ways to trim down the collection so that you don't seem like some crazy, obsessed, board-game hoarding nut job (cue the "I'm fine...I can quit any time!" line). If you're worried about being considered a nut job, I have a few helpful tips to assist you in trimming down your board game collection to only the absolute necessities (and maybe one or two guilty pleasures too).
1. Consider Similarities: I like deck-building games and worker-placement games the most out of any options, but I don't need toown every single one I've ever played. Take a good, hard look at your collection and spend some time considering what the games have in common, and what each one offers individually. You can have multiple deck-builders; there's theme, player count, and difficulty to factor in, amongst other things, so it makes sense to have more than one if that's a mechanic you enjoy. But, if you find that you own a fair few games like that, and some are just a little too close to call, think about getting rid of one or two so that you don't have to keep choosing between them. Just keep your favorites!
2. Think Before You Buy: This goes along with Tip #1, but also helps to encompass expansions. I love having the ability to expand on some of my favorite games, but not every game I play is in need of an expansion. Before you buy every add-on to Settlers of Catan or Smallworld, weigh how often you actually play the base game. If it comes to less than twice a month, you probably don't need more add-ons to the same game. Save the money for something more useful.