Yes, libertarians support legal gambling. The state should never hinder the business exchange between a casino or gaming establishment and an individual.
While some oppose gambling on moral grounds (such as Christian libertarians), libertarians support the free enterprise of gaming in accordance with the philosophy of free-market capitalism.
A business such as a casino has a right to offer games of chance to its customers. Rational actors (that is, willing participants) may choose to indulge in or abstain from the services provided by the gaming establishment. It is their choice.
While libertarians support an individual's right to patronize casinos and gaming establishments per free-market economics, some invoke the libertarian virtue of self-discipline if the rational actor (gaming patron) has become self-destructive, losing more money than they can afford to lose.
Libertarians who invoke the virtue of self-discipline declare that liberty is only possible when an individual lives a moral and ethical life conducive to freedom. If they are destroying their life with gambling, they cannot truly be free.
Moral questions have been raised by conservatives concerning libertarians' stance on recreational "sin," suggesting that societal collapse results from an inability to temper hedonistic desires, thus resulting in less freedom macroscopically.
Libertarians contend with the conservative argument, steadfastly supporting an individual's right to moral agency. Libertarians conclude that individuals are free to decide how their lives should be lived, and the government should not legislate morality.
For more information see 'What is Libertarianism?'
