"What's right isn't always popular. What's popular isn't always right."
-Albert Einstein
I think what he is trying to say  is that when your popular people make you take bad choices. And if you take the right choices it won't make you popular. So its better to do what is right then been popular because making the wrong choices could lead you to consequences. Consequences could really affect you and your life.Doing the right choices could help you a lot in life and way more persons would have trust on you then the popular persons.