The special foiling, the lore pips across the card, there's so much making this card beautiful that it's no surprise it's so expensive
While it's been power crept out of playability, it still has a nostalgia factor that contributes to its value
For competitive players, buying singles saves $200-400 vs opening boxes to pull needed cards
Even when they do offer affordable starter decks, these are often too underpowered to hold their own against established players decks
While the effect of Din's last ability is applying, your opponents can choose not to attack with a creature that must attack if able as long as there is no other player, planeswalker, or battle for that creature to attack that wouldn't require a cost
Just like the raw card marketplaces, graded cards have public/visible markets and private/hidden markets