There are many ways for fake casinos to appear live and display logs of numerous bets per second. I think they're more skilled at this than real casinos.
Running a real casino is more complicated than one might think, not just marketing, but also technical aspects (responsiveness, reliability of gaming machines), liquidity, and so on. Scammers often operate solo, which clearly doesn't meet the criteria for a full-fledged casino company even if they planned to.
The betting logs on the homepage and the online user counter do not prove anything. I have seen new casinos that show like 1K, 1.5K, or more players are playing the same game. There is no way they have that many active player playing their games in the first month of the launch. They just fool the players, and unfortunately, the players fall for their tricks. Even if someone falls for them after seeing the number of online players and fake bet history, the player should flag the casino the moment they ask for a deposit to verify the account. I have seen dozens of such cases on Reddit.
You are correct about the real casino operations. Yes, they do need many people. But doing marketing is not easy. Traffic solves the 50% of the casino business, and you have to handle the rest with your team. It seems these scammers are experts to bringing traffic.
