Gambling can be a sin. It's not inherently wrong. Lack of self-control is a sin, and most gamblers have times where they lose control. But I don't see anything wrong with making intelligent wagers, just like I don't see anything wrong with trading stocks or options.
(1) Gambling discourages honest labor. The Bible supports the concept of the so-called "Protestant work ethic."
Proverbs 14:23 (Amplified) tells us, "In all labor there is profit, but idle talk leads only to poverty." Profit should come through productive labor, not by chance.
"Wealth not earned but won in haste, or unjustly, or from the production of things for vain or detrimental use, such riches will dwindle away; but he who gathers little by little will increase them"
Proverbs 13:11 (Amplified). See also
Proverbs 28:19.
(2) Gambling encourages greed, materialism and discontent. See Luke 12:15, Hebrews 13:5, I Timothy 6:6-10, Psalm 62:10. Lottery promotions induce people to covet the money of others. Gambling such as lotteries are engaged in by people hoping to win a lot of money without earning it, which is a dishonest attitude. Money won in gambling comes from other players, including some who can ill afford to gamble. Gambling in its essence is a form of robbery, which is stealing. Each gambler wants to get the prize money for himself. It encourages greedy obsession with material wealth, which is having another god in place of the true Creator. Gambling directly breaks the first, eighth and tenth commandments, and all the others in principle.
I John 2:15-17, "Love not the world neither the things that are in the world. If any man love the world, the love of the Father is not in him. For all that is in the world, the lust of the flesh, and the lust of the eyes, and the pride of life, is not of the Father, but is of the world. And the world passeth away, and the lust thereof: but he that doeth the will of God abideth for ever."
Proverbs 21:25-26, "The desire of the slothful killeth him; for his hands refuse to labour. He coveteth greedily all the day long: but the righteous giveth and spareth not."
(3) Gambling encourages "get rich quick" thinking. See Proverbs 28:20, 22; 21:5.
Proverbs 23:4-5, "Labour not to be rich: cease from thine own wisdom. Wilt thou set thine eyes upon that which is not? for riches certainly make themselves wings; they fly away as an eagle toward heaven."
(4) Gambling encourages reckless investment of God-given resources. See
Matthew 25:14-30. If gambling is "fun" and "pleasure" to you, you already have your reward. If you are denying yourself, serving the Eternal 100% with your time and resources, you will not make the pitifully weak (and false) excuse: "But I have a right to throw away my money at gambling!" You know that your life, your wealth are not yours. If you follow the Bible, you are a slave to the Messiah. You, your money, everything you have are His. Would Jesus gamble? Definitely not!