Being a Soviet/Russian conscript is a terrible fucking lot in life. Being raped, beaten, denigrated was and remains extremely common. You're taken from wherever you had probably spent your whole life, thrown into a shitty uniform, shipped off like cattle to wherever it is that the motherland needs you, and used as an inanimate tool until you were either too broken and destroyed to function anymore, or you had managed to survive to the end of your term.

Alcoholism was and remains rampant, and in many cases even encouraged, as to keep the system 'lubricated'. Getting shitfaced on whatever you could find that'd get you there quickly is just an extension of that.