Gambling is not wrong. If you play the lotterry is it wrong???
The real problem is the gambler itself. Some people loose it, others don't. Another problem is cheating betting casinos and sites, and all the violence and illegality behind it.
Yes in some countries lotteries are banned and according them it is wrong. In your country may be not banned but in India not all kinds of lotteries are allowed but only some government regulated ones are allowed. People are very easily addicted to these gambling games so if one don't know how to control himself it is better to stay out from gambling.
Yes in India single number lotteries are banned because many people lost lot of money so government has banned selling any single digit lotteries quit long back.
Gambling is not wrong if any one know how to control them self and when to come out from gambling. If you think you can easily an attracted by these gambling games than better don't start gambling.