I'm the first one to reject the title "theologian" when it comes to my role as a Pastor-Administrator, and I'm a little nervous about giving theological advice. I'm business trained and educated and a pretty good student of the bible but trying to determine exactly what God would consider sin is not one of my talents.
Of course there are many that oppose buying a lottery ticket as it's really the equivalent of gambling (knowing somehow that gambling must be sin). I'm not too sure if playing the lottery is gambling. The likelihood of a lottery ticket paying off is so low even the government looks at the purchase of a ticket as the equivalent as making a "voluntary contribution to our schools and senior citizens". While I'm still not willing to venture into the discussion on what makes a sin a sin, I do recall back when I was working on Wall Street that some of my Christian friends felt that even "playing" the stock market was gambling and as a result was sinful.
I assured them (and my wife!) that I was working and I wasn't "playing". My employer paid me good money to be a good steward of the funds that were entrusted to my care. I was able to define the difference (actually a chasm) between buying stocks and gambling. Stocks are purchases of small bits of equity or ownership in a company. Stocks are also purchased in the hope (not guarantee) that the shares of stocks will be worth more money in the future. There are differences between putting money on a blackjack table or in buying a lottery ticket and buying stock. Investors in the stock market buy shares in a company in order to participate in the profits of a for-profit enterprise. Gamblers are counting on luck and chance, for if it was a skill or based on knowledge it wouldn't be gambling.
The difference perhaps comes down to intent. Isn't that possibly the defining line for sin as well? Jesus said in Luke 6, "The good man brings good things out of the good stored up in his heart, and the evil man brings evil things out of the evil stored up in his heart. For out of the overflow of his heart his mouth speaks." If we have a good heart, or have good intentions, we'll be doing good things. The Bible gives us plenty of examples of good things. We don't have to worry too often about the grey areas that are not specifically mentioned in the Bible.
I think one of the reasons that some would look at the Powerball Lottery as being evil or sinful is that it does resemble a "get rich quick" attitude. That is typically not a good attitude for followers and disciples of Christ. Proverbs 28:20 says, "A faithful man will be richly blessed, but one eager to get rich will not go unpunished."
While it's not bad being rich, much of the Bible's teaching about wealth is a warning against putting trust in wealth rather than the Lord (i.e. 1 Timothy 6:17-18) or to the detriment of those who depend on us (i.e. Ecclesiastes 5:13-14). The New Testament teaches that we are to be good stewards of all that God has entrusted to us which includes our money. Jesus spoke often about money and riches and we should be careful to love people more than things and to hold very loosely all that God has given us. In this way, when we have opportunity to use our possessions in ways that the Lord brings to mind, we won't hesitate to instead keep our possisions to ourselves.