Understanding is the main thing that must be paid attention to before they decide something, as you said that we must be ready to accept defeat and that doesn't mean we are ready to just win, I would say you are a coward and irresponsible if you only want to win but don't want to lose. Controlling expectations and limiting them will be very useful to stay safe..
Of course those who think only winning in gambling they normally lose the most. There are some gamblers who do so much research that seems they will not loss. But when the results of their bets show up their reports convey great loss. I think there are times when you have to accept where you're sitting on the losing side but if you're lucky you can get big rewards. After getting a win in gambling one must prepare to lose. If luck is good there may be a chance to win a second time. Every time you win, your chances of winning will decrease and you will have to accept the loss. A gambler can never ignore loss.
Never at all, gambling owners who bring out their business knows and understand the big chance of making money they did not create it as a giveaway to everyone who will play the game, I like that idea of accepting both side so you'll not going to keep chasing your losses and may have a better chance of enjoying your gambling activities, like what OP said, gambling is not a safe haven as chances to lose mostly happens especially for those who got greed and forget to set up their limitations.
They will not create a casino if they know they would lose their money with it that's why casino always have the advantage compare to their players. That's why people should never take those words or comments that some people earn a passive income on casino especially if they are playing on random result since nothing like that exist. That's also the reason why other caught up on wrong expectation then think about they could always win on casino but end up chasing their losses because they want to recover and quit.
That's why we should have good expectation about gambling so that we could not expect for more but instead try to make those winnings as inspiration to create better gameplay but target also to have fun so that we can get satisfied on whatever result came to us.