We All Accumulate A Lot Of Things
As we go through life we all accumulate a lot of things, the thing that we sometimes forget is that some of that stuff could quite easily turn out to be a collectible item. Something that we buy at the time might not seem to valuable, but give it a bit of time and these things are very sought after.
It could be something that you got as a Christmas gift for him, you know something you picked on a whim, then becomes really popular and now every one wants one. Or it could be something that eventually attains a cult status, and so value goes up.
There are lots of reasons why things become collectibles, it is not always obvious to all of us, because all people have different tastes. But when something you or some one you know owns is worth a lot, you then have the decision as to whether or not you sell it. After all if it has been bought as a gift, it is not easy to sell it on without feeling a little bit guilty.
In this case it might be worth talking to the person who gave it to you, and making sure it does not hurt their feelings.