You are right if it was just a simple bet on one number. But I suspect the article is skipping out on the full description. My guess is that it involved a system where multiple bets were placed each spin - Roulette's odds can be narrowed if you place bets on a color, a third, high/low, and a number, making sure to minimize doubling down on any possible result. That puts you in a position where almost every spin, one of your bets wins and offsets some other losses. When the spin lands on the bets with higher payouts, you win more and balance out the spins where you got lesser payouts. All told, you'll slowly lose money all night, and one of two things happens - you one number hits and you win big. Or the zero hits and you've lost. It is a very complex and pain-staking way to flip a coin. But, if you have any way to game that one number, and can afford to just let those bets ride for the hours for that advantage to play out... I could see it working.

Also, back before casinos were computerized, people did spend years learning the specific machines in a specific casino. They would often do it in teams, so each person would take an 8 hour shift, and share the winnings at the end.