Do you have the same opinions for stock market investing at your house?
In a Casino, at some point you have the cold hard cash in your hands. This makes a big difference. Secondly, there are lots of barriers in your way, for example maximum withdrawl on debit cards, actually having to queue up for cash for the nth time as supposed to just clicking a button, actual time to mentally prepare (you need to get there, plan your money - it's harder to 'impulse' gamble from location x) etc etc.
Stock market by far was the most damaging, and the most exciting especially when you get into leveraged forex plays or options. The big barrier here for joe public though is the order of magnitude higher complexity to actually make a gamble over an easy to understand proposition (like a horse).
For now stock market gambling is probably OK due to it's general inaccessibility, but there is a big move into making it more accessible: so called "Social trading" for example.
The platforms are significantly more accessible to average punters who I believe are going to increasingly start using these services for gambling, because these places are actually thinly disguised gambling houses. The spreads they offer are ludicrously expensive, the promotions they offer are aggressive (and borderline scam), and the marketing message sucks people into a false sense of security about what activity they are actually engaging in. This is in my opinion the big danger in the future. It's hard to lose your house at a casino in one go, or with online poker. Plausible to lose your house in one single bet gone wrong in Forex/Options and the social trading platforms look pretty and friendly.
'Social trading' in my experience and opinion is pretty damn irresponsible, and is executed pretty damn unethically. What benefit the offer society and their users I've yet to see apart from getting a nice adrenaline fix.
That's not what i've seen in modern US casinos. It's been a few years, but I remember people using cards for slot machines. The image I remember most was a man in a wheelchair with his card on a lanyard around his neck. The card was in the slot machine. He looked physically tied to the machine, never moving except for one finger on a button. It looked like something out of the matrix.
Almost everything we used to physically undertake can now be achieved online, with perhaps the exception of physical stimulation by a third party, and that's probably not too far away. Society needs to realise that if there's gambling at bookmakers on the high street, there's going to be gambling online. As another poster has suggested, the US should consider legalising and then regulating the activity, not continuing with prohibition.
Of course there will be people who suffer addiction and financial issues due to online gambling problems. In the same way, there are people who can't stop surfing porn, who can't stop messaging/texting/updating Facebook while driving, who basically now never leave the house because they're on their arse surfing the Net at home. It's not going to stop.
There are many, many positive aspects to modern connectivity. It is how society deals with the negative aspects of online culture that is important.
The expected value of trading stocks is at least slightly positive. If you invest totally randomly, you will, on average, win more money than you lose. You still lose money in fees and stuff though. But you are at least starting from a positive sum game with a positive expected value.
Gambling is the exact opposite. It's all a zero sum game. For everyone that wins something, someone else is losing something. At best it's exactly break even.
Look at Uli Hoeness, former manager of FC Bayern. He fucked up big time with leveraged deals, lost all his gains and had to pay taxes on gains which no longer existed, netting him a stint in jail instead.