An old coworker of mine had an ultra pro stack, I want to say maybe ~30 inches wide and quite tall, made by international at the time I think, tip over on him because he tried rolling it over a large crack in the floor. The caster plate basically folded in on itself and the box fell over, he was able to straighten it out enough to still use for another couple years, he had a ton of tools in it otherwise it probably would have been fine.
Another shop I worked in the old foreman had one of those no name stainless steel boxes costco sometimes sells, full of junk that was quite literally collapsing in on itself. All the ball bearings slides fell apart and it was sagging badly in the middle.