As an adult, I've been able to periodically buy gigantic and expensive Lego sets, which I started doing just before Simon was born. The joy in those is the construction process. I would never be interested in building one of these sets and sticking it on a shelf somewhere. I'm not that "Lord Business" from The Lego Movie.
Well, not exactly. I am careful in that I want to maintain the integrity of the sets. I also want it to be reasonably easy to build them again. Someone asked what I do when it's time to disassemble them. Basically, I take them apart by following the instructions in reverse, to numbered bags, as they were when I opened the box. The time varies a lot, but it's usually not more than 25% of the original build time. Some sets go a little slower if the division between bags isn't clear, but some go faster. The Disney Castle, for example, is completely sectional, and the 4,000 pieces come down pretty quickly outside some of the detail work. Probably less than two hours. The new roller coaster (pictured below), took a little longer because it's not obvious where the bags split, and there's a lot of detail work with small pieces in the scenery.
Yeah, it's extra work, but it's worth it. The kits that are particularly mechanical in nature are really fun, and engage my brain in a pleasing way. The Ferris wheel in really cool. The castle ins't mechanical, but it's architecturally neat. You can't roll with too much chaos for 4,000 or more pieces.