What was the most significant factor in the causation of the October 1917 Russian Revolution?

Firstly, we need to decide what the main factors were. They can be defined as the failure of the Provisional Government, the role of Lenin and the Bolsheviks and WW1. Ultimately, Lenin and the Bolsheviks carried out the revolution and as such we can argue that they were the most significant factor. Indeed, they carried it out alone, inciting many historians to label it a coup instead of a revolution. However, they wouldn't have been able to do so without the weakness of the Provisional Government and WW1. The Provisional Government did not have the people's support and indeed, during the Kornilov Affair had armed Bolshevik prisoners in order to defend the city. Thus they were a weak opponent for the Bolsheviks to face. However, arguably WW1 was more significant. Germany ensured Lenin's safe crossing to Russia in the hope that Russia would pull out of the war following the political chaos that they hoped would be enacted by Lenin. Moreover, Lenin gained supporters through his promise of peace and as such, arguably WW1 was the most significant factor in causing the revolution. The coup like nature of the revolution suggests that a people's uprising was not inevitable in October, thus in Germany sending over Lenin as a result of WW1, the war must be considered the most important factor.