Guide 1: Why crypto currency exists

The Problem

Today, the majority of trade is global. You might buy a kettle from Japan and ship it to the UK, or buy a coffee in Kenya when on holiday from the USA. 
Paper and electronic money do work today, but they have many issues, for example:  
There are 180 different currencies. Converting the Kenyan shilling to the USA dollar is expensive and costly.
Everyday we learn about a  new 'hack' or 'data-leak'. Keeping electronic/digital data secure is getting harder.
The value of a countries currency is linked to the government. If there is instability that value can dramatically fall. 
Converting and spending your currency requires it to flow through many 'middle-men' which has many hidden costs. 
We could continue to use paper and electronic money going forward; we could also continue to carry gold and silver coins with us. They're all just less easy than it can be. So let's now ask the question:

Why does crypto currency exist?