50,000 euro cents = 500 Euro.
This is a valid stamp, accepted by the Austrian post office.
Theoretically, you can use this stamp to pay for up to 500 shipping fees (ie. send a parcel through the Austrian post office)

Plus 70 bucks for the gold, so theyre losing money on this? Thats why I was questioning it
I guess, they rely on the fact that this is a collectible item, and almost no one is going to (actually) use it to dispatch items with. So, they are selling 500 Euro stamps, that very few will "redeem" the service value of it.
But still, those 500 Euro are not gone from the books. They have to keep them in accounting records and can't use them for something else. But I also agree, that they make profits by selling products/services, in this case the crypto stamps.
