Another point Page made is quite good: nobody controls the system, but everyone influences it.
Given this, there is no way to know how much good YOU can do in the world: who you can influence, what you can do, what you can start.
Always do your best, given this, even if all your work–all OUR work–appears futile. Appearances can be deceiving, and the overwhelming Left may one day evaporate almost overnight. That is certainly the fate they deserve, and the one that would most contribute to generalized human health, wealth, dignity, happiness, and freedom.