You dont understand it, its only overpriced TOO YOU.
Other people might think the card is worth more and others might think its worth less.
The card has no inherit value, it has the value each individual puts on it.
If he wants to put it from someone who valued it at 20k and sell it to someone who values it at 30k he can, neither are wrong.
Its a free market, its worth what you think it is.
Business is all about profit in fact one of the most well known quotes in investing is "buy low sell high"