Believe me, not all humans are the same, even if most are. While I respect the admission that you are making here and trying to educate others, you need to be aware that not everyone in the world is like you with these things. It is for sure true that people cheat themselves with smoking, drugs, gambling with the just one more time lie. But there exists a fair proportion of people in the world who are the exact opposite, to quit something they may need to make it a memorable occasion and by assigning big importance or value to the last time they just do that. They get their closure, they enjoy it or believe to enjoy it just one more time, and then they say goodbye and never look back. So while your advice is true for a large portion of the population, it is not true for everyone. Those that need such final and meaningful closure will most likely not be able to stop without it.
Yes, when we lose money through gambling within our means, it does not create a big problem, but when we start gambling beyond our means, it creates a big problem. It is very important for every gambler to setting boundaries before gambling, in this way, one can protect oneself from the additional risk of losing money and can limit oneself to one's means and maintain self-control over oneself, as a result, gambling can be conducted according to the right rules and one can protect oneself from the dangers of gambling and can enjoy the fun along with gambling for a long time, so it is very important to gamble by setting time and money.
I question this vague definition, because what does it mean within our means? A person that wants to lie to himself can always change the definition loosely to avoid admitting that what they are doing is wrong. If I burn all my discretionary income in gambling this month, that is still within my means so if we go through your definition it is not a big problem when in reality it is a huge problem. Gambling should be limited to strict and small budgets, and not loose definitions of within our means because that can be a lot of money.