You can't cure a need for distraction by blocking domains. There isn't a cure. You have to learn to live with it, like alcoholism.
The good news is that major life events tend to be great for breaking the distraction seeking pattern. At some point you'll get married or have kids or change careers, etc. And then your life will be so different that looking back on a dns kill switch button will seem silly.
Until then, just keep pushing the button I guess. We all have to make it through somehow