  Ponzi schemes are financial frauds which lure users under the promise of high
profits. Actually, users are repaid only with the investments of new users
joining the scheme: consequently, a Ponzi scheme implodes soon after users stop
joining it. Originated in the offline world 150 years ago, Ponzi schemes have
since then migrated to the digital world, approaching first the Web, and more
recently hanging over cryptocurrencies like Bitcoin. Smart contract platforms
like Ethereum have provided a new opportunity for scammers, who have now the
possibility of creating "trustworthy" frauds that still make users lose money,
but at least are guaranteed to execute "correctly". We present a comprehensive
survey of Ponzi schemes on Ethereum, analysing their behaviour and their impact
from various viewpoints.
