Here's a great article on all the issues with cryptocurrencies:
"Ten years in, nobody has come up with a use for blockchain" by Kai Stinchcombe
http://hackernoon.com/ten-years-in-nobody-has-come-up-with-a-use-case-for-blockchain-ee98c180100"Everyone says the blockchain, the technology underpinning cryptocurrencies such as bitcoin, is going to change EVERYTHING. And yet, after years of tireless effort and billions of dollars invested, nobody has actually come up with a use for the blockchain—besides currency speculation and illegal transactions.
"Each purported use case — from payments to legal documents, from escrow to voting systems—amounts to a set of contortions to add a distributed, encrypted, anonymous ledger where none was needed. What if there isn’t actually any use for a distributed ledger at all? What if, ten years after it was invented, the reason nobody has adopted a distributed ledger at scale is because nobody wants it?"
He basically looks at all the purported advantages of a cryptocurrency, and finds that there's something already well-established that does the same thing for much less.
Want to make payments without a middleman? Use cash. Want to make payments online? Visa can handle some sixty thousand transactions a second, compared to Bitcoin's historical rate of seven. And the power requirements for those seven transactions are estimated at 35 times what Visa needs. Scale up Bitcoin to where it handles the same overall volume as Visa, and it would need the electric output of the entire world. Sure, Visa skims a tiny percentage of the transaction - but for that, you get things like fraud protection, buyer and seller verification, and the ability to get a refund.
"In the end, the advantages of the existing human and software systems surrounding transactions — from verifying identity with a driver’s license to calling and clarifying the statements made in a credit disputed transaction to automatically billing your credit card for a newspaper subscription — outweigh the purported benefits, as well as hidden costs, of irrevocable, automated execution. Blockchain enthusiasts often act as if the hard part is getting money from A to B or keeping a record of what happened. In each case, moving money and recording the transaction is actually the cheap, easy, highly-automated part of a much more complex system."
How to prove "one person, one vote" without any blockchain nonsense: