Any revolution you study in history has causes that are all similar. There is one group who has more than another. The more is usually at the expense of those who have less. Without sounding too nebulous, revolutions result from the following factors:
Lack of food or necessities to live.
War
Rights of people who feel repressed.
Neglect of a government to take care of its people, or resolve the issues of the people at hand.
Profiting off of others' work.
Corruption of power with violent consequences for dissidence.
Lack of upward mobility in society.
Vengeance for a family member killed.
ALL of the above.
The Russian Revolution was really a series of revolutions that dated back to 1905. Among the events was a revolt aboard the battleship Potemkin. The crew were forced to eat spoiled food. The Russians were defeated in a war with Japan, which emerged as a naval power. In addition to two wars, there was famine from weather. The Tsar was deposed for not managing the famine properly. However, that first revolution of 1917 was not the immediate overthrow that had the communists take over. That would take place in October of 1917 during the Bolshevik Revolution that dissolved the provisional government led by Alexander Kerensky.
Famines of the early 20th Century
Provisional Government under Kerensky
The tyranny it seeks to replace becomes tyranny.
Ideas behind the revolution may be corrupted.
People may be reeducated to the new society or executed outright.
Deposed regimes in an area may touch off a civil war.
More people may die after the revolution.
What stabilized the region now creates instability.
Other factions that fought in the revolt may fight for their freedom.