High quality, historical, gold coins are getting harder and harder to find (and exponentially more expensive to acquire) as they are being scooped up by wealthy collectors and gold investors.
As old US coins become scarcer, and therefore more expensive, old foreign coins (and paper currency), are growing in popularity, desirability, and value.
This coin, especially being gold, will only increase in value. This coin can only go up in value and desirability, especially so as it it is certified.