I don't think I have ever owned more then 3 pairs of shoes of any kind let alone all those mountain boots. I guess my style of buying a pair of hiking boots and wearing them until they are falling apart and then just buy new boots isn't as common.
Ummm, no, I think that it is pretty common to purchase new boots as the other(s) wear out. In my case, I own one pair of heavy winter boots for snow-shoeing/crampons/other devices & a light summer mid-rise for all the rest of the year. Some of my friends have started to get into those (disposable) sneaker-type low tops, but I have no use for such a specialty item.....any more than two pair of boots would start competing for closet space with my 100 pairs of heels.