Why did Allah make bad people?

In the Qur'an it says that Shaitan disobeyed Allah and we should make sure we do not fall in the trap of Shaytan as Adam (AS) and Hawwa did. Why doesn't Allah make sure we do not do things which he doesn't want us to do since he has power over all things? I know this is a test and we are supposed to learn from Shaytan's mistake but at the same time I don't understand why Shaytan has been allowed to have so much power. The good people will be rewarded and the bad punished but why did Allah make bad people? Why didn't Allah just make good people?