I wouldn't say they had an easy time of it.

First, keep in mind there were two Russian revolutions. The February Revolution was the one that overthrew the Tsarist government, and it was a very large, broad-based movement, at the height of a ruinous and unpopular war rife with food shortages. When even his own Army turned against him, the Tsar abdicated. A Provisional Government was formed as a result of this revolution.

The October Revolution was when the Bolsheviks overthrew the Provisional Government. The Provisional Government was already very weak, not extremely popular, and fractured into factions. The Bolsheviks took advantage of that and seized a lot of the infrastructure and means of government in a very direct and organized way.

Even then, how "easy" was it? Well, easy enough that the country became embroiled in a terrible, bloody, five year civil war as a result. The Russian Civil War can be thought of as a stage of the October Revolution, the final consolidation of power. It was not until 1923 that the Soviet state was really, finally established beyond a doubt, and it was a very ugly transition, one which laid a lot of precedents for things to come.