I know that as gamblers, everyone can relate to this question, as we have surely experienced it in real situations.
Suppose our bankroll is $100 and it has already grown to $500, would you quit or continue? Conversely, if with our bankroll, we are down to $10, would you still continue or save the remaining $10? I used specific amounts to make it easier to discuss this situation. I understand that we all gamble with different amounts based on our income, but consider this as an example. You can mention any amount you want based on your personal experience; it doesn't matter.
When to stop gambling depends on how you control your gambling. If one is involved in making money then it becomes really difficult to get rid of gambling. There are many who go to the point where they can't control their greed in order to get profit from gambling and thus they face losses instead of profits from gambling. There is another class of people who go to the point of losing money, where they keep betting repeatedly to recover the money they lost earlier, and eventually become bankrupt, but still cannot stop themselves from gambling. That is, no matter what we say, those who can control themselves from gambling can refrain themselves from gambling under any circumstances and those who cannot control themselves cannot control themselves from gambling under any circumstances.
Some of the points you have given for regulating gambling are correct. First of all you should abandon the tendency to only earn money while gambling and start taking gambling as a form of entertainment. If you gamble for fun, it can reduce your risk of spending money and prevent wasting time. This method can be much easier to control if you can add it to gambling. Second, you can limit time and money allocations such as a particular money allocation and time allocation per week to reduce the risk of losing extra money. Thirdly you have to rely on luck most of the time to win while gambling and if you lose you should withdraw yourself immediately. Basically gambling control is entirely up to you and you should plan your activities accordingly.