The primary draw of Galarian Perrserker is its ability to add more damage to all your metal-type Pokemon.
This means that it can be used in top-tier decks like Zacian V, Melmetal GX, and Metal Saucer. However, since metal decks haven't been too upfront lately, this makes market investors a bit cautious, which does keep the price tag at the reasonably low levels.
The future of this card depends on how well the metal decks will do this season. If things go really well, then expect an inevitable price increase, and if the decks based off Galarian Perrserker's damage don't find a place in the meta, then it should drop to about $10.