Friend isnt being himself...?

Well it seems you have two choices: standby your friend until he finds himself or cut ties with him and move on. Apparently he feels that his brothers life was appealing to him, but many have been deceived by thinking the gr is always greener elsewhere. I would not get into an argument with him. Just tell him in a calm manner I care for you and I like the person you were the funny and kind person. Remind him in the past he never had to work or change to be your friend. Hang with your other friends and if he wants to tag along let it be his choice. Eventually he'll see where his true friends are. The more you push the more defiant he will be to push you and the others away. Every now and then check on him and let him you guys care. Good Luck