High Relief silver investment coins

I have been interested in investing in precious metals such as gold and silver for 3 years. My interests focused mainly on bullion coins - the cheapest. Those that are easy to verify, recognizable around the world, easily marketable. Recently, expanding my knowledge in this area and trying to diversify my portfolio more, I am looking for information about premium and super premium silver coins. On the channel: https://youtu.be/miBmOY67qjk

I watched a video about coins from The Witcher series. Here we enter a completely different section of investing in metals, because the price of the metal is of little importance. Here we are talking about collecting unique and limited mintage of 2000 coins.

What do you think about such investments?

How big do you think is the risk that this series will turn out to be a flop or a dud after some time? The current price of this coin at various online auctions ranges from PLN 4,500 to even PLN 8,000.

https://mennica-gdanska.pl/pl/monety-swiata/2701-ostatnie-zyczeń-wiedzmin.html

Others in the series released in later years also increased significantly in value.