Jackpot

 

A jackpot is a large cash prize won in a game or lottery, usually accumulating until it has been won.  The term was originally used in a form of poker, where the pot accumulated until a player could open the bidding with two jacks or better. A jackpot is usually an additional prize to the regular prize and can be extremely large -  hence the "get rich quick" lure of them. By the way, "Jackpot" is also the name of  an unincorporated town in Nevada and popular casino gaming destination.