So, it's basically a super-de-duper reverse Tactician: Get a blowout turn now, forfeit all your other turns for the rest of the game. In principle it seems interesting, but in 2-player it will just be the other guy playing Solitaire for the rest of the game.
The natural next step, mathematically, would be something that costs $17 and gives 21 VP. Maybe:
Conqueror
Victory - $17
Worth 1 VP
When you gain this, gain 2 Colonies, setting them aside.
I do see the point about the card turning the game into Solitaire, but if you're at the point where you're able to get $74 (and a Potion) in hand at once through various means, which doesn't really happen that often, you're probably either neck-in-neck with your opponent in some sort of a Dominion version of an arms race or you've absolutely stomped your opponent into the ground and you're going for a final mega-turn.
This could be a completely incorrect assumption of course, as I don't really see myself as an expert in the game, but in my experience, just getting to or above $20 with some extra actions or buys (if available) is usually seen as a mega-turn, and getting to $50+ is seen as a stratospheric sort of mega-turn and is usually a lot rarer (than getting to somewhere around $20).
The tl; dr version of the last two paragraphs I guess is that the card is designed to introduce a sort of "final blow" mechanic to the game.
(Which is why the it states that there's one less card than players in the stockpile, meaning that there'd be only one Smite in its supply pile in a 2-player game)