A casino tells you the exact odds, and everyone is freely able to decide if they want to play given those odds. Yes, they are in the house's favor, but that is what a player trades in return for the whole setup (the casino, the workers, the free drinks, the entertainment, etc)
You can still argue casinos are immoral, but they are clearly not a scam. That would be like saying cigarettes are a scam, just because they are bad for you.
The house can claim malfunction on anything and refuse to pay you. You have little to no recourse. I've witnessed people having their jackpots declared invalid for ridiculous reasons such as a faulty door sensor on the machine (having nothing to do with the game itself.)
You're essentially gambling that you can win the game and the house won't deny your win.
If you see a casino cheating, you should report it.
If a casino catches or even suspects you're card counting, they are well within their rights to refuse to let you play that game anymore.
If, on the other hand, you and the casino are playing different games, e.g. the dealer is playing black jack, but the player is playing I-know-what-the-dealer's-down-card-is-because-of-manufacturing-imperfections-in-the-card, then is it really that unreasonable for the casino to have a case that they don't owe you the money that you won, especially if they can demonstrate intent? (I'd argue that they should give you a bug bounty, but that's a different story)
To address your poker example - say I'm your guest in your hypothetical and, were we playing fair poker, your 1 in 100 odds were correct. Let's also say that I have undetectable X-ray vision contact lenses, thus changing the odds such that I will always win - would you really consider it unreasonable to use the government to get your money back in that situation? The agreement was to play poker, a game which necessarily presumes hidden information from all players. If one player has all the information, the game isn't poker anymore, it's robbery/con.
I agree that the computerized games are a different story, though I believe that consumers have some protection in the form of the various gaming commissions. If you win a jackpot and are denied the payout, contact the gaming commission! The laws are very strict on the points of fairness of those machines, forged in the fires of decades of mafia controlled casinos (at least in Vegas/Atlantic City).
Gambling is a drug. It has all the health benefits of a recreational drug, but at least in (most of) the US, it's not a scam.
Yes, sometimes casinos will use their political strength to not payout a jackpot (malfunction voids all play), but a player does, in fact, have some recourse if the casino is full of shit.
Regardless, if you're going to a casino intending to win a jackpot, you're doing it wrong (because math). If you take a measured approach and enjoy it for what it is (entertainment, not a way to make money), you'll have a much healthier relationship with a casino.
As an aside, there's another industry that uses it's massive political clout and every trick in the book to refuse to pay in situations where one would intuitively believe one should be payed: insurance.