If we're being honest, Cobra always drank a lot. His first paycheck was an assortment of energy drinks and Jager, IIRC.
When he lost his job at Wendy's, he worked with Warlord in the dish pit but when that fell through and he was convinced to start his wand business, that's when the deterioration started. He had no schedule, no structure to his day, no NEED to be sober since he could just stay at home and get hammered. He learned that he never needed to work; donations, wand money and government cheques could do just nicely. Ever since, it's been a slow decline where he became more and more depressed, more and more drunk. Wands stopped going out frequently, albums were spaced out more and had less effort or passion applied to them. Less interaction with the world because he never needed to really leave and less people coming to see him because the light in his eyes was dying.
He didn't just lose that job at Wendy's. He lost the social pressure to be sober, to try to act normally, the structure of life that brings some peace. Every step after that moment was a step towards death and the worst part is that Josh knew this, admitted this and embraced it.