Most of the gamblers who make money out of gambling are good in money management. When one has the ability to manage his fund and stay within limits, then there is more chance of money making than losing. Because, he knows where to stop, take a break and when to have a new session. This is not possible and can't be followed by every gambler. This is where gamblers differ in money making and these people aren't greed to make big money within a short time period.
Not denying that, money management is important if you are an investor, trader, gambler or just a person trying to make a budget, my point is that money management skills are a skill that is defensive by nature and it helps you to maintain your capital but it does not help you to increase it by itself, for that you need a completely different set of skills and most people are unable to get them, which means that we need to be happy to just enjoy gambling for what it is, an entertainment source.
But it doesn't mean you are a good money manager you will always win in gambling, gambling is truly based on luck. If you are not lucky enough on that day, you will come back after in the next day when you feel better because handling emotion is the best practice in gambling.
Gambling makes us sometimes fun, but we should have our responsibility to manage it whatever happens and don't follow on greed that will surely turn to addiction and the last part is becomes worst your life or becomes miserable. So, it really depends on us on how we control ourselves. Because it doesn't mean gambling is your source of income since it is popular right now.