Some governments are waking up to the dangers of cryptocurrencies in their present free-for-all form. Vietnam has banned payments in cryptocurrencies, South Korea has banned initial coin offerings and anonymous accounts, and China is cracking down in numerous ways. Other governments, including ours, are urgently studying cryptocoin regulation, which may be on the G20 agenda in Argentina next month. My fear is that the bigger cryptocurrency gets, the more legislators (and their backers) will own it, and the harder it will become to regulate it in a way that benefits all of us rather than a handful of us.