Up until 2017 I had a collection of just over 500 kits. I had to sell them in bulk that year due to an ongoing financial & personal crisis that took a very long time to stabilize. I have to say that selling off the stash was one of the worst days of my life. I was under no illusion that I'd ever build them all. But just having that collection in my possession was something really special to me and it hurt bad having to sell it. Here's a general idea of how it looked back in the old house. Keep in mind too that there were also quite a few more kits added to the pile AFTER these pictures were taken 
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There was lots of good stuff. Mostly ranging from early 1990's vintage through to the mid 2010's. I rarely had shelf queens, or put together a few parts & then got bored and put the kit away. I didn't do kit-bashing either; the most I ever did was (for example) steal a headlight guard from a Tamiya kit if I broke the one on the Dragon Sherman I was building at the moment. The only other "odd" thing I did was almost always take the parts out of the internal bags because I was worried the bag plastic would shrink over the years and distort or twist the parts up. Apparently this "reduced the resale value" according to some. But I didn't care about any alleged "collectors rules". Those kits were my babies and I didn't buy them just to put the box on a shelf and forget about them
My current, but much more logically-sized stash is less than a dozen kits. Inflation, even the regular general yearly inflation that happened in the economy before COVID, simply prevents me from ever building up a collection that size ever again. It's just too cost-prohibitive and can't ever be repeated, barring a magical lottery win happening someday. And that's definitely the best way to approach this hobby IMO. I'm more than willing to admit my buying when things were much better in my life got way out of control. The way I did it wasn't even obsessive, it was just stupidly habitual. Having nothing out of it by the time it gets all said & done isn't something I want to ever repeat.
PS - make an accurate list of your collection with each time you buy a new one! I didn't and making a list from memory takes a long time, like I did a couple of years ago, even moreso when dealing with those absolutely awful websites companies like Dragon have where they have barely a fraction of the products they've issued over the years properly listed. Thank Jaysus for the service provided by Scalemates though when looking up a kit you may have had once upon a time!