I can definitely understand stuttering leading people to substance abuse. Luckily for me, drinking does not improve my speech or confidence. I never tried cocaine or anything strong because of my fear of addiction. I abused energy drinks and caffeine early in my 20s to power through stuttering, and that's about as far as I've gone. Ultimately, you've got to accept that you stutter and recognize that no one is without problems. People don't care about your stutter just like you don't care about whatever they've got going on that you may or may not be able to see.