Having good discipline might not make you win more in gambling because many games are purely luck-based, but for games that don't completely rely on luck, I can definitely see confidence being a good thing for your chances of winning.
If you've got extremely weak discipline, you probably shouldn't be gambling in the first place because you're more prone to gambling more than you can afford. Gambling's certainly nothing to mess around with, especially when many people get hooked and can't stop, and others that just don't seem to learn from losses and continue to do the same thing over and over again in an attempt to 'earn back' their losses and more. A long time ago, I also used to rather recklessly gamble my money, and though I get less adrenaline from gambling now compared to then, I get a better feeling afterwards knowing I've still got plenty of money left compared to nothing or almost nothing.
If he means about discipline is being disciplined to manage the bankroll such as to cash the money out & stopping to play for a while everytime you hit a win to reduce some pressure, emotions and greedy inside yourself then I might tend to agree that this discipline manner could always help you to gamble healthy responsibly , that's the point to risk your money in gambling without risking your whole personal life as it's quite often happens when someone gamble emotionally undisciplined they are ended up with crazy bad things as worst as suicidal attempts or at least ended up in huge debts.
Being disciplined is more than just helpful in gambling, it would help you to get a better character in person overall.
Should we be disciplined in gambling, does it mean that we are better at gambling, or that we put less money at stake with more enjoyment, less fear, adrenaline, etc. ?
Me interested in answering the last question?
I can't see any relation between being disciplined to putting less money , less fear but to purely considering gamble as entertainment, am I missing your point?
But if you thinks that which one better between staking more money vs less money to get the entertainment in gambling, I'd say less money releases any fears to go against the odds , to go against the majority and to make you disciplined ... as for the result, you'll play nothing to lose.