I agree with Gee, it's not all about keeping them sealed - heck, I have barely anything sealed (I much prefer to open them and admire the contents and display them

) but some collectors take pride in their sealed items, more so than if they were unsealed - not because of resale value, but because that's the condition/way they like their collector's items to be
As long as you are doing it for
you, and not purely to make a profit in the long run, then you are a collector

xx