Its possible that despite his sarcasm he cares about him and doesnt want to see him squander his money.... or he is just flabbergasted by his lack of smarts.... or both.?
His brother is stubborn and indecisive. Love doesn't negate reality. We are who we are. As was said - he's a grown man. Figure it out. It's like asking someone to tell you if the dinner you're buying will taste good. How the F would anybody know 'til you order and take a bite?