You're hearing this from a puppet. My epics and ultra-rares are sitting in this account. I don't intend to sell them, and I instead want them in my "main" account. Just so all my ultra-rares/epics/legendaries are all in one place. Not to sell, because again, I just like collecting. But rather as a good storage unit.
So then why do I have to pay a huge fee to get these cards into my main's collection? I can't really elaborate much on this beyond "Well it's more convenient that I just have all my good stuff within one account for aesthetics."