Online gambling has two features which make it better than going to casino to gambling. First is Privacy as no one knows that you are gambling and second is ease of gambling where you can gamble any time 24/7 without any hassle to go physically in casinos.
While we can post a lot of advantages of online gambling, there's two disadvantage of online gambling that online casinos cant do anything, that is internet access and electricity. Without this two, online gambling is useless. Thats why in third world countries, even electronic games are rare, playing cards is still their way to gamble.