Stated a little more neutrally: give at least some care what you spend money on in the context of what you're making and what resources you want to have left when you stop working.
Because most people really, truly, honestly don't need the shit they think they need; they just "want" stuff more than they "need" it. Adopting this mindset helps you have cushion for catastrophic problems if/when they arise.
And typically the number one thing that negatively affects a person's financial situation is the state of the national/global economy, that is, something entirely outside their immediate control. Thus having a nice cushion for something outside your control is a pretty good idea.
Watch Robert Shiller's OpenYale courses. They're amazing. Particularly the last one* in which he mentions that, to reiterate, that most financial problems most people face are economic circumstances completely outside of their control. The causes of which are financial institutions inability to properly deal with risks which then causes massive economic inequality that we see today and which is growing larger more so today than it ever has in history.