People believe that paper/plastic money can trade for a thing they want. It is a shared belief. Taken for granted and we assumed it is the right thing to do: socialisation and the power of shared culture. We used to trade items, like shells, or pigs, but money gives us what we want, and there will be no more troubles. But if you look at someone that has lots of money, sometimes, they feel this is not the case, for to get money, you must work hard, long hours and have little social life. So, money might give you things, but it may not provide you with happiness.