An important point is that drug users (alcohol included) lose their ability to judge their own impairment after a lot of habitual use. They can even develop an

An important point is that drug users (alcohol included) lose their ability to judge their own impairment after a lot of habitual use. They can even develop an ability to appear sober to casual observers while being impaired. Feeling sober is not a reliable indicator of being sober. It’s referred to as delusions of sobriety.