Why are people on the internet worse than people in real life?

There are a few explanations.

1. Since much internet communications is typed with people not being able to actually see or hear each other. With this personal aspect of conversation removed, someone might be inclined to say things that they would never say to someone's face.
2. Many of the people that say hateful or inappropriate things on the internet may be the sort that, frankly, don't get out much and so you are less likely to meet them in real life.
3. Many inappropriate comments are posted by a relative minority of the population, but these people tend to be more vocal and so are more easily noticed.