Because of bitcoin’s ‘public’ construction, it needs a defence against miscreants and so uses “proof of work” to make it computationally difficult to add a block . This has created a value of mining and therefore a need for incentivisation. Close to 40% of the world’s inhabitants, some two billion individuals, wouldn’t have entry to a bank account. The mobile phone is starting to alleviate the issue and blockchain might be one other massive driver.