Handling Emotions When Dealing with Difficult People

So I took a class today on the above title. It was all about "Me Do". Basically, their point was like the famous quote - "No one can make you feel inferior without your consent.". All well and good and I will try their strategies. But although it goes against my normally logical attitude, I still don't see why "difficult" people just get to continue to be difficult while the rest of us have to strategize on how to deal with them. I admit though, you can't change others, you can only change yourself. We'll see how I do.