The best I have seen for why we shouldn't gamble is this...
1 Timothy 6:7-10
7After all, we didn't bring anything with us when we came into the world, and we certainly cannot carry anything with us when we die. 8So if we have enough food and clothing, let us be content. 9But people who long to be rich fall into temptation and are trapped by many foolish and harmful desires that plunge them into ruin and destruction. 10For the love of money is at the root of all kinds of evil. And some people, craving money, have wandered from the faith and pierced themselves with many sorrows.
Solution as well.
8So if we have enough food and clothing, let us be content.
... with what you have.