Is there anything else in the bible that says not to gamble? That one quote is a tad ambiguous, as it also says in their that it is easier to fit something big(don't remember what) through the head on a needle than it is for a rich man to get into heaven. So maybe they are encouraging us to gamble 
I'm not sure,
I know that in the old testament theres a lot of talk about peter losing a lot of gold in the old phillistine opium dens etc
King Soloman banned all types of gambling in the 3rd century bc, as God told him in a dream.
I think a lot of gambling being percieved as being bad, is about lucifer being the controller of mans luck you see.
Max Van Sydow told Jerry sizemore in the film "The Greatest story ever told" that, it was easier for a camel to go through the head of a needle than a rich man to go the kingdom of heaven.
Hey what do I know though..