The cryptocurrency industry is getting so big and enabling so much risk-taking that governments around the globe are taking notice.

Bitcoin traded above $50,000 on 24 August; its total value now exceeds $900bn, more than all but a handful of companies. Digital currencies called stablecoins grease ever more trading and issuance. Giant crypto exchanges in Asia offer 100-to-1 bets, often serving traders in countries where their products aren't legal.