Its like being a card counter at Blackjack in Las Vegas
Blackjack is one of those games that the odds only very slightly favour the house if everyone sticks to the accepted roadmap
You can win at Blackjack, just knowing the basic roadmap you've only overcome small odds. The House is fine with this
Card counters have modified roadmaps for the amount of picture cards left in the shoe, these roadmaps swing the odds away from the house considerably
The House hates card counters BUT card counting is not illegal nor is it cheating.
If the pit boss suspects you're a card counter, your night is over. "Excuse me Sir, No more Blackjack this evening, you are quite welcome to play any of our other games". Of course the card counter just walks out and tries his hand elsewhere, he's interested in the odds being in his favour, none of the other games really are (even Roulette, has a slight edge for the house (0 and 00 effectively)
Gambling establishments don't like it up 'em