Why do people live in tornado zones?

There's good farmland in many of those areas.

The chances of a strong tornado hitting any particular spot, even in a place such as tornado alley, are actually relatively low. On average, about 60 people in the U.S. are killed by tornadoes each year, which is fairly low compared to other causes of death.

Additionally, no matter where you are there is always some sort of risk factor, whether it is from tornadoes, earthquakes, pollution, or crime.