Why did Communist Russia win the Russian Civil War?

When assessing this question, it is worth taking into account the natural resources and geographic factors which gave Lenin's government an inherent advantage. A good starting point for this is that the territory the Reds controlled was central and interconnected, meaning logistics were easier. Second, the reds gained a substantial amount of material power through controlling Petrograd and Moscow. This is due to there being substantial arms stores in these cities.
In contrast it is necessary to look at the nature of the White movements lack of resources. It is though perhaps necessary to nuance this argument. It is not the lack of resources which external forces had but rather a lack of willingness to use them. This limited the white war effort.
Whilst hard to quantify there was also a value in the fact that a substantial proportion of the white movement was international, so Lenin could frame the movement not as a communist defense, but rather as a defense of the motherland. Thus meaning Lenin could garner more support in the short run.
Finally the agency of Trotsky could be analysed as a possible factor. Innovative and mercurial leadership skill. Able to run an effective fighting force.