You don't go into gambling expecting to make bank from this activity. I understand that it can happen, but it's just not the right mindset in my own personal view. And even if you keep playing, it's not realistic at all to expect to keep winning all the time.

Even if it's just sports betting, playing poker or plain old luck based gambling... Chances are, you'll be a loser sometime.
But it must also be pointed out that at least to some extent OP is right. As overt emotion doesn't help do almost anything with the right mindset. So anyone wanting to try gambling they must know to limit themselves and not go overboard with money they can't afford to lose. Being too emotional surely doesn't help.