I can explain why some traders want that hat of yours so much. Since you are talking about pre-order promo items, they just happen to be worth exceedingly large amounts of currency during their debut, which is why the traders want them, they want to resell the item to gain profit, or make money. I can't guarantee this, but if it were me, I would resell it.
For an explanation or the "overpriced" hat, many people tend to buy hats like that. An example of this is the concept of
"unusuals". The reason why people buy these kinds of hats is next to inconceivable to consumers, as they tend to view things from a "utility" viewpoint, which means if they cannot find any use of it, it's worthless to them. This is how you are viewing it. However, the traders view it most likely from a "profit" point of view, meaning that they want to find a way to make money off of the thing they bought. In other words, wait until the prices of that item increase then sell it so they make extra money from their item they bought.
As a side note, what makes you think that I will mess with your valued hat? I never mentioned anything about messing with it. Anyway, I just thought I could try to explain the reasons traders makes rather strange trades like the one you mentioned before. As another note, this is just my viewpoint. Also, sorry for the wall of text. I feel guilty of it. This was all to answer your questions, also to sort of unblow your mind.
I have gotten so many trades like this before it's starting to become less of a lucky trade and more like my regular trades. It's just the only way around. Like when I sold someone 1 hat for 1 hat worth 3.33 ref and the guy also added like 5 trading cards. Cool right? This was actually one of my best trades! Plus I sold the trading cards and the hat! I believe that the hat that I am mentioning is called "The attendant" It is a wonderful hat, plus it's value.