It's not even simply a money / burnout thing. Space and time are a huge concern. Even the wealthiest Lego fan in the world (not me) probably doesn't want to spend 8 hours a day just building everything they felt compelled to purchase.
I've hit the point where I have unbuilt sets piling up, some of which I've had for years (current rolling record is 5 years, 5 months). I'm either going to have to dismantle some sets to make room, or just give up and sell stuff. Maybe UCS sets - they used to be special when they were the largest, most adult-focused sets TLG made, but now they're just some among many others.