Well this just became a huge regret of mine, so I thought i'd share with you guys.
About 2 years ago I was really into the Team Fortress 2 Unusual hat market (Some may know what it is)
Well anyways, back then I had traded my way up and obtained what I thought was my final hat. After a while I got bored of TF2 So I decided to sell the hat. At the time it was worth $500, so I straight up sold it for that.
I recently revisited the site that I used to trade/sell on, and I see that the EXACT same hat that I had owned 2 years ago has just sold for $3000.
Lol, that's what I get for being an impatient fgt I guess, still sucks knowing if I just held onto it that I could of sold it at a giant profit.
I wouldn't worry man, there's no way you could have known. Like any currency - you could have come back 3 years later to sell it only to find it going for $5 instead of the $500 you sold it for lmao.