Law #20: People will constantly and consistently underestimate the impact their very being represents.
Here's something I get to witness every morning on my way to work (mainly since summer is over). There's a high school on the road that I have to drive on and every morning it's backed up right to my street (I'm on 6th; it's on 1st). The reason the traffic is so bad is because not only are kids constantly crossing the street to get to the school, but also drivers are dropping off kids as they pass it (who subsequently cross the street). So what's the point of all this as compared to Law #20? It's that the individual actions of each of those people culminate to create one huge clusterfuck. I like to use traffic as an example but people don't seem to realize that if other people follow suit and do something they just did it accumulates and multiplies. That's definitely not always a bad thing. If one person votes and everyone else follows suit huge changes can happen.
You see we often like to think our actions are singular and they don't really affect anything. Well you're not alone buddy. Literally. And they're out there thinking the same thing. That the individual things they do ultimately don't affect the big picture. They do. Individual actions add up and ultimately inspires huge changes.
