For better or for worse gambling will definitely affect you mood and behavior. I've seen the most common example being that people are more neurotic and hasty with their decisions, sometimes even hysterical just cause they couldn't for the life of them not let gambling rule their lives. On the other hand I've seen people become more responsible with their money, with some even being able to set up spending allocations and budgets as well as financial planning which they got from gambling.
Gambling can change you. but don't let it be for the worse. We have enough people in the looney bins already, make sure you don't become one of them.
The remark that "For better or for worse gambling will definitely affect your mood and behaviour" is not always applicable as you quoted it, it depends on the gambler, his plan for gambling and the mindset at which he is gambling as well. For me, I always say it's relative because, for example, I don't feel a single thing when I gamble with casinos. Do you know why? It's because I don't ever believe that I can make big money from it. So, this mindset has been helping me for so long and has helped me to prepare my mind and my budget for casinos accurately without mixed psychological feelings. Nowadays, I bet with a very low amount of money with casinos, this is because my mind has been resolved on the fun part that I can derive from it, but not money.
This is why I am convinced and I say it practically that I feel nothing about casino betting. I just don't have a better feeling for the money made and a worse feeling for the money lost as you put it. But for my sportsbook betting, yes, I must say that it often affects my emotions a bit, it's a bit because I mostly gain in it, though I do not bet anyhow, I carefully select my games and I do not put my mind in the result no matter what the outcome states. Maybe that is why it doesn't affect me, and I implore everyone to do the same. The better part is that I do not bet huge money on regular matches but only on crucial matches like the matches that decide the final. UCL final is an example. So, people should try to tame their feelings as much as they can, it's possible, it's about planning and discipline and how they can control their feelings and bet reasonably.
You literally just fleshed out what I meant. For better or for worse is relative to what the gambler has in mind at the very moment he made that gamble. You see what I mean? People gamble with an ulterior motive, you don't just gamble out of nowhere for no reason at all. That itself will determine whether you're bound to be a gambling addict, a neurotic one at that mind you, or a responsible gambler who knows what their limits are and what they can and cannot bet on.
I mean it's on you if you don't feel anything from the money you got from casinos and gambling, I myself share the same feelings but only cause I know that besides the fact that it is money I know wouldn't last me a long while, it came out of someone else's pockets too. As for your sportsbooks betting, and I'm saying this with the premise in my head being you also watch and are a fan of the games you place a bet on, you're probably mixing the feelings of winning/losing the bet, with the feelings of your favorite team or just the team you're rooting for in particular being in the winning or losing side. And even that is an indicative of what I just said.