well getting fired from a job for being drunk all the time is definitely a red flag for a drinking problem. you can express your concern for your friend that you are worried about him drinking too much that it is taking over his life. if you say he is stubborn, he is unlikely to listen to you but at least you have expressed your concern. the seed will be planted in his mind. offer to help him find a counselor, go to AA meetings with him, help him find a treatment center. let him know he is not alone in finding help. have these resources available before you talk to him so you can give them to him. good luck.