Is it accurate to say that investment has come to more closely resemble casinos or gambling parlors than areas of investment?
No I don't think so, investment banking today is complete from what it was 40 years ago. If you look back to the 1980s the lifestyle of a banker was much closer to that of a gambler from the Hollywood movies than it is today. Back in the days banker would do anything to get their hands on a deal, going to strip clubs with clients, doing cocain and hiring prostitutes was part of client management. In 80s there was much less compliance, regulation and oversight. All the major deals were discussed in some cigare lounges among white man
Today there is a much higher demand ratio among bankers, so the game changed a lot. Also the public is much more sensible about stories of bankers being involved with prostitutes and drugs. And Warren Buffet likes to do business with wall street, he was the one who bailed out Goldman Sachs in 2008 and made a lot of money with his loan.
The difference you pointed out has nothing to do with the nature of stock market. What have changed are just some superficial ways how people behave, nothing related to the nature of business. Metaphorically speaking, just because you are wearing a new suit today does not mean you are becoming a different person.