The 0 confirmation is basically a marketing tactic so if a gambler loses all their BTC and they are on the tilt to revenge gamble then chances are they will if the deposit is confirmed fast, if it takes a few hours to confirm they might get bored and stop gambling and stop losing money. If it comes right away they will gamble it instantly and might lose it also.
Yeah it works, there are tons of people who does exactly this, there are also tools that make it easier as well, I have sold something to a double spender before (they legit paid me because I would have cancelled their subscription if they didn't) but I have watched him literally pay for food with double spending and get the money back, he didn't had to because dude was rich as hell but he just wanted to show off I guess.
So, the double spending happens in bitcoin to this day, exactly the method you talked about and they make a ton of money from unsuspecting casinos, casinos think there is a ton of people who lost their bets but they realize there isn't that many btc in their accounts and when they figured it out most of the time it is already too late.