If you make money on your own, you have a job you get a pay check, if you work for yourself, you support yourself with your own business, chances are if you're responsible, you're going to spend your own money in a responsible manner. Because if you don't, you're going to pay a price for that. No pun intended, but for your own irresponsible spending. And have less money than you otherwise would've had on things you need to spend money on to survive, had you spent your money responsibly. So knowing that you're most likely to spend your money in a responsible way, when your spending others people money, you should spend it in the responsible way that you would spend your own money. Not believing that you can take more chances with other people's money.
Especially if you're spending someone's money and they give you more money and keep giving you money. You're not going to be as responsible generally speaking, because mistakes you make with other peoples money, unless consequences come with that spending, won't effect you the same way. As the persons whose credit card, or checkbook, or even cash that you're spending. So you're going to be more likely to make mistakes spending other people's money than your own. Because it doesn't come with the same consequences. The Federal Government is a perfect example of this and why it wastes so much money. 100B$ a year alone in some programs and departments alone according to GAO.
Because the Federal Government doesn't make a dime on its own, all of its revenue comes from tax collection. Plus since it controls the U.S. Currency, it can print money like drunk sailors spend it. Giving it even more incentive to waste money and spend it irresponsibly. I bet you anything that if the Federal Government was a business and I'm not suggesting it should be, that they would be a lot more efficient with the taxes it collects. I'm not making a case for not having a Federal Government, or making it weak. But what I am suggesting that it have solid rules on what it spends the money on that it collects. And that there's strong oversight from Congress and the GAO, or Government Accountability Office, on its spending and operations to cut back on the waste in it.