Large parts of Europe at the end of the First world war were revolutionary: factory occupations and worker councils in northern Italiy lasting for two years, in 1919 Hungarian Soviet Republic and Bavarian Soviet Republic were proclaimed, Germany was basically in a civil war (see for example about Freikorps, murders of Luxemburg and Liebknecht)...

All of the above were ended in part through internal opposition, but outside military interventions played a key role, be it from international forces as in Hungary or from within the same state but outside revolutionary areas, as in Germany and Italy. Similar foreign intervention on the White side in Russia failed, for reasons I won't go into but were covered at least few times on this sub.

Basically, early Bolshevik beliefs that October revolution was just a first of wider European or even world revolutions was not as far fetched as it seems when other socialist revolutions are forgotten. However, counter-revolutionary forces, both internal white para-militaries such as Freikorps and international interventions, were more easily organised and concentrated in those countries than in vast and peripheral Russia. Additionally, Bolsheviks were able to mobilize not just revolutionary socialist sentiment, but also anti-czarist, anti-war and peasant forces. One of their central revolutionary and Civil war moto was "Land and peace", that is "land to those that till it" (peasant goals) and ending Russia's involvement in the First world war.