Recently Tesla’s stock rose by almost 5% per cent, pushing Musk’s net worth up to $183.8 billion. This makes the self-styled celebrity the world’s richest man, surpassing Amazon’s infamous Jeff Bezos. For Musk’s cult of free-market fanboys this simply proves his genius – a fair reward for the world’s most brilliant inventor. But what is really behind the Tesla empire? And what has Musk actually invented?