Anyone using the wallet is actually mining, either on their phone or there desktop. If it can be mined on mobile phones, then it's sustainable, rather than worthless. That's how it should be. The requirement to purchase expensive equipment should not be necessary to have access to generating cryptocurrency, and is in fact the sign of an inefficient means of energy and financial alocation. Bitcoin introduced the world to proof of work, and since bitcoin has become ubiquitous in the marketplace, that's all people know. Federated Byzantine Agreements are completely different, and magnitudes less energy hungry. Just because something can be mined on a mobile phone, doesn't deem it worthless. If people use it, then it has value. The monetary system has value because that's what we agree to use as a medium of exchange, but if a shop for example, accepts a precious rock as a payment, then that precious rock has value.