Why do people invest so much?

Different people do different things, what kind of answer are you looking for, one that will describe and explain actions of all people?

You spent 5 bucks in December on a coin, how do you know you lost? Have you sold it for less already, why? Wait for the price to go up, sell part of your coins to refund your five, wait some more time...

Look at some posts here to be in the loop on when to sell.