They're there to make profit off of it, just as I'd like to profit off of their service; after all, that's what exchanges do, too.
Although you have to be careful, both can benefit you.
There might come a time when they return your bitcoin in fiat instead of the bitcoin that you put in. Like for like, as they say.
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Just like comex dose
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Well...you have heard the stories of comex. How many times have they given fiat even though the person wants the metal delivered? They arent storing much. Its probably an empty vault.
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