This is because silver bordered cards are essentially jokes, which means designers are allowed to bend and break the card frame and design standards to fit as many ridiculous things as they want
Try not to play out your hand all at once
There's also the matter of this being a deck built around expensive cards in general
When you rely on very specific cards to win, the risk presented by Demonic Bargain is considerably more dangerous, as exiling a key card can take you out of the game instead of creating a significant inconvenience
The most expensive creature in the deck is Dockside Extortionist, with the second most expensive being Neheb, the Eternal
Burn spells arent just for burn decks, either, and many burn cards find their home outside of them