Is the questioner considered negligent towards his brother, whom he brought to work in Kuwait, then left the job and returned to his home country twice due to his extravagance and inability to manage money?

You are not negligent by being keen on your brother's well-being, advising him, and wishing good for him. You can direct him to work by seeking help from the elders or close friends. You can also ask him to lend you some money periodically, then ask for his approval to invest it.