In the Sega Genesis version of Disney's Aladdin (1993), the player encounters a merchant on multiple occasions who will offer either an extra life for every five rubies Aladdin collects, or a scroll labeled "wish" for every ten rubies. What benefit does the scroll labeled "wish" offer?
From this guide - "A wish gives Aladdin one continue. That means when he loses his last life, he can continue the game from the level he is at instead of having to start over. Every time you continue a game, you get the same number of lives as when you first started the game. A wish could be worth up to 6 extra lives."
So since a continue is worth so much more, it makes sense to save up for them instead of just regular extra lives, if you can.