Radicals had existed in Russia for many years, and there were no shortage of liberals who opposed the autocratic government of the Tsars in favor of a representative government. But if anything produced the Russian Revolution, it was the actual conditions confronted by the Russian people in 1917. Russia was fighting in an unpopular war, and suffering one disaster after another (including a few while the army was commanded by Nicholas himself,) and the people were suffering massive casualties. More important, Russians, especially in cities, had to deal with privations, including food and fuel shortages.
It was in this context of widespread misery that the Petrograd riots broke out, sparking the chain of events that drove the Tsar from power. Many of the revolutionaries were socialists and liberals, but the extent to which ideals compelled the first wave of the revolution seems fairly minimal. Ideas were important, especially in mobilizing striking workers, but for many who took to the streets of Petrograd and elsewhere, the Revolution was about more fundamental issues than ideology. Anti-autocratic ideas had existed since the Enlightenment in Russia, but it took popular discontent based on hunger and poverty to drive the Tsar from power.
As the revolution went on, and reached a new stage with the Bolshevik overthrow of the provisional government, a small cadre of revolutionaries who believed strongly in an ideology came to power. Part of this ideology was a belief in the destruction of the system of social relations that characterized the autocratic rule of the Tsar, even though he had abdicated in the wake of the Petrograd riots. The nature of land ownership, in particular was a pillar of privilege under the Tsars, and this was a major target of the Bolsheviks, who called for "peace, land, and bread."