I think the digler999 simply means significant differently than you do. A 40% chance, for example, could still be interpreted as significant. Numerous casino games when played optimally give you a better chance than that of winning or breaking even.
It would be interesting to see what the likelihood of being up after an hour of regular play is by different common games.
In addition, games like poker aren't even played against the house; you're playing against the other players (and the house just takes a cut as a sort of "table fee"). If you're a skilled poker player, you can reduce the effects of luck (what cards you get vs. the cards others at your table get) and come out ahead more often than not.
And I'd agree that even a 30-40% chance of coming out ahead would be "significant"... people in the startup world still start new companies despite the conventional wisdom of a 10% success rate.
Having said that, sure, casino games are pure entertainment. Sure, you can win a little money, but you should never expect to, and you shouldn't play unless you're comfortable losing every cent you put into it.
The last time my wife and I were in Las Vegas, the only game we made money on was sports betting.
A slot machine with an expected per iteration loss of .1% and a modest 100 iterations/hour, would, over that same hour lose you (just) go over 9%.
The more independent small bets you make, the lower the chance that you will come out ahead.
vegas can afford to turn their hold percentage much lower because millions of people go there every year and there's competition. Versus a lone indian casino in california's central valley.