The rest 499 are being given away through various competitions. Currently, running competitions are (might be more, but I am only aware of those):
1) scan QR codes in different physical post office locations in Austria, and fill a competition form. 2) Weekly draws, based on the online digital token "collections" (you have to check every week your digital stamp collection, and redeem the "golden unicorn" within that week period, in case you won one).
Yes, I won one in the onchain raffle. I randomly checked my collection a few weeks ago after reading this thread, and WOW, I had one sitting there waiting. I filled it out and what not, but nothing yet from the post. On the other onchain stamps I redeemed, they send me "Invoices" showing the amounts and card types, and the first one I got told me I had to wire them 99 EUR ... I was like, what? So @Jcga informed me it was an error, and now the invoices come with a big X over the part that says to send them the $.... This is such a yearly clusterfuck, I think I'm out this time. With ALL of the problems these 2.0 stamps have had, it's hard to say/see what next year/3.0 will look like.
I wonder how many people missed the unicorns in their collections and lost out.... And what happened to them if not redeemed? So many questions