Roman emperors received the blame when things went wrong: war, economy, famine, etc.

Emperors were replaced or murdered when disruptions in Roman reign occurred

in 50 years, from 235-285 A.D., 50 different emperors ruled Rome

Roman lands in modern-day France, Spain, and Britain prefered to be ruled by local rulers and broke free of Roman rule and started the Gallic Empire

Order was hard to restore and Rome began to see problems in its empire

The Roman economy was starting to fall due to constant war and infighting (fighting amongst themselves)

Trade was stopped during wars and Roman agriculture was not adequate (without its imports from other surrounding lands) 

Higher taxes and food shortages plagued the Roman Empire

Rich and poor Romans suffered, but the poor took it harder

People were angry and criminal gangs began to sprout

Romans were not interested in official jobs because it was too risky (beatings and killings of government officials)

Everyone was looking after themselves

Rome became too large  for the emperor to govern it effectively 

Rome stretched from modern day Scotland in the north to the Sahara desert in Africa to the south and to modern day Spain to the west and as far east as Persia

Rome's constant defense of its borders used up resources and drained Roman funds

Rome was fighting in the east against the powerful Parthian Empire in Persia

Germanic tribes attacked Rome's northern borders

At home, different groups were infighting to decide the next emperor

Roman civil wars drained it of food, money, and soldiers

Raiders attacked unprotected borders and took riches from the Romans

Rome and other Roman cities had to build up their defensive city walls for protection