[throwaway22032]

The issue is basically this:

If you have issues with impulse control you are likely to become poor because you will slowly bleed out money and opportunities from bad decision making.

The opposite is also true: it’s just less correlated because it is harder to gain money than to spend it, so not everyone makes it.

This is obvious to anyone who grew up poor and escaped, or who grew up well off and watched people on the fall. How long does a middle class heroin addict remain?