Prosecuting cases with cirstantial evidence?

I know many case are just cirstantial evidence, but still I do not see how a case can be prosecuted like this. I still do not see how Scott Peterson was found guilty with the evidence. The media won this case, not the prosecution. I just do not see how a theory is good enough for a conviction when there is no supporting evidence. For instance, you have a burglary, you find prints inside of the location, they are matched to a stranger that had no permission to be inside of the house. You search his house, find nothing, you have no witness, no confession, no stolen goods are ever found. Now how can a conviction for burglary be obtained? The prints prove that the person was inside the residents at one time, maybe during the crime maybe before maybe after. All the DA would have is a theory, nothing else. Hell the defense would have a theory too. Now are cases now solved by theories and not facts? Even though that person had no permission to be inside, there is still no proof that he/she stole anything or actually committed the crime, or even was there during the crime. Once again how is cirstantial evidence good evidence? One last example, you find fingerprints on the murder weapon and later match it to a person. Now there is a good possibility that he may be the actor, but with no other evidence there is nothing but a theory of cirstances. Even if the suspect and the victim had a beef the prints still do not prove that the person killed the victim. Sure, anyone with a good imagination good develop a great story and present that to a jury. Once again, how can this happen without supporting evidence?