Your main lines of play revolve around sending characters on quests for Lore, then using powerful shifts and songs to protect your board
Skill Cards let you become your favourite YuGiOh
The Ozolith feels like the perfect way to keep all of your counters after a board wipe, making it much easier to get back into the game
I know this is far from the best deck in the meta, but it's super fun and can win games.
Finally, there's probably a small group of players who want the cards for unique reasons, like building an Un-set cube (which becomes a lot more realistic with three Un-sets rather than two) or even Un-set collectors, which I'm sure exist in some number, although this last group has to be pretty tiny
As for this particular variant being so expensive