Well, I'm only one person, but for what it's worth, I like buying trains in their original boxes. Other things being equal, I will always buy the train with a box before the one without a box. I just think it's fun to get something new (or new-to-you) and take it out of its box. It's like Christmas! Many on this forum proclaim that they have matured beyond having fun of this sort, but not me. And I suspect I'm not alone.
So I keep all my boxes, but I flatten them and store them in plastic tub(s) (just one so far, but will be starting another soon). Flattened, they're just a stack of cardboard, and you can get a lot of them into a small space. I have reconstituted a few, and they were just fine. Since I already have an inventory of my collection, it is trivial to add a note of whether I have a box, whether it has been flattened, and what number is on it (since that is not always the same as the number on the car).
