Gambling was initially illegal in most places but now it is officially licensed in many countries. Now it is considered as an industry.
Yes, gambling has changed with the development of technology. Once a time people used to go to a casino to gamble physically now they can play at home. No one but the gambler himself can know the amount he has lost or won. In general, security is really high.
Gambling became legal in many countries because the government realized that they are wasting a possible huge income earner for their country. Rather than gangs and syndicate taking advantage of gambling profit, they then decided to adopt gambling as a legal industry.
Another piece of gambling history. Did you know that it was only in 1991 when 24-hour gambling first allowed on a trial basis in Atlantic City casinos? Before this was enacted, the casinos had to close several hours each day. [1]
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https://www.funtrivia.com/en/Entertainment/Casinos-Gambling-6258_8.html