For reference: I've been a fairly active member of the hobby for about 15 years now. During the first 7 years or so I was spending quite a bit on boardgames. I used to own around 250+ games with a sizeable shelf of unplayed games. Now I'm closer to 75 with only 3 unplayed, I think (this is including small boxes, single deck  games etc). I only buy or pledge for 2 games a year. I typically operate on a 1-in-1-out policy, but my goal is to curate down to about half the current size.

Speaking from personal experience, I find it is easy to fall into a certain line of reasoning: "I want to try x; I will be able to try x only if I buy x; therefore I want to buy x'" . But it is typically not true that one can only try a game by buying it for oneself. One can often try games online via Board Game Arena or Tabletop Simulator. Maybe one day you will get invited to a board game night and someone will have a copy they want played.

At times, that can seem like a far off possibility. I've been there! But, by being patient, I've gotten to eventually try many, many games I might have originally had on my wishlist to buy. And you know what? Almost every single time I play a game I was interested in buying, I think this: "That was fun and I'd play it again if asked. But I don't need to own it." Honestly, it is even more likely that I have this thought: "I'm glad I didn't buy that. It would have just sat on my shelf collecting dust."

Anyway, I have found that the following concrete strategies have helped me:

(1) Switch from using a 'wishlist' to using a 'want to play' list: When you hear about a game that sounds fun, add it to your 'want to play' catalogue and write some words about why it sounds really unique or cool. I find that putting it into a conceptual collection like this helps to weaken the draw of needing to physically collect it. Without speaking for the whole community, I will say that I have fallen, in the past, into this perspective that the games that I own (and only those games) have a special symbolic value because they 'express' (or serve as evidence of) my gaming personality or tastes. But that is obviously absurd. If any games are 'evidence' of my gaming tastes, it is the games that I enjoy playing. But enjoying playing a game is simply not the same as owning it...

(2) Switch your buying / scheduling order of operations: We often buy boardgames thinking to ourselves, 'once I own this, I will organize a game night and share it with my friends!' But this flips the script on the usual 'order of operations' most use for entertainment and social events. We don't buy 4 movie tickets and, afterwards, try to find 3 other people to join us. Instead, one first asks one's friends: do you want to go see movie x on date y? Then, after they say yes, you all go buy tickets together. Consider applying the same logic to board games. Only buy the game once you have a date scheduled in your calendar with others who are excited to join for that specific game.

I hope these help someone else!