Historians figure that at most 3% of the Colonial population actually took up arms.
Another statistic used a lot in American Revolution history classes is that only 1/3 of the colonial population supported the cause. 1/3 road the fence, while the the other 2/3 of the population were about evenly split along loyalist and revolutionary line. Interestingly enough, this is almost the modern day break down between self identified liberals, independents, and conservatives.
In short, small groups of dedicated people can control and or change historical events.