That's the common line of the losers, they can't accept that casinos are winning and they are losing.
With house edge, they can win most of the time, but they'll never win all the time, but if you are gambling with a house edge, it's expected that you'll lose in the long run as you don't have the edge, it's pretty simple, so I hope they'll understand that before gambling.
I'm not sure I understand what are you trying to say. If it is expected that you'll lose in the long run(and by the "long run" we mean millions of games played, right?), you shouldn't gamble at all? Is that what you are saying?
I personally think that it would be more right to say that it is expected that casino will win in the long run, but it's not necessarily that casino will beat you in particular.
Most likely they were saying is that Gambling is a selfish business that all they care is about the money of players, which is normal because that is why it's called "business". However, those players who are always losing concluded that gambling sites or casinos will never let you win but will going to take all your money, which again is normal.
Casinos or gambling sites works that way because that's how they make bankroll every single day. Gambling sites never force anyone to play, therefore gamblers are the one who is responsible for their actions, whether they win or not.