You may have heard the saying "nice guys finish last", but there is plenty of evidence that says being nice is far more advantageous. This video explains why being nice is almost always the best way to go.
First off, we need to identify what "being nice" means. Generally, being nice is following the Golden Rule, which means treating others the way you would like to be treated. It's about reciprocation and being helpful, as opposed to being persistently selfish. This video, from the AsapSCIENCE YouTube channel, explains that being nice has some science behind it. In a classic problem known as "The Prisoner's Dilemma", two participants square off using only two cards; one saying "defect" and the other saying "cooperate".
When you break it all down, participants tended to play their cards selfishly, with "defect" always being the best option for oneself. When scientists ran extensive computer simulations, however, the most effective strategies involved being much nicer. Playing "tit for tat" -- or treating the other participant the same way you're treated -- ended up being the absolute best strategy overall. The video also points out that being nice -- or animals treating other animals how they would like to be treated -- is a major factor in nature and animal groups as well. It's important to look out for yourself in the world, but being kind is always an effective strategy.
Nice Guys Finish First [YouTube]