  Blockchain systems need to solve consensus despite the presence of rational
users and failures. The notion of $(k,t)$-robustness has shown instrumental to
list problems that cannot be solved if $k$ players are rational and $t$ players
are Byzantine or act arbitrarily. What is less clear is whether one can solve
such problems if the faults are benign.
  In this paper, we bridge the gap between games that are robust against
Byzantine players and games that are robust against crash players. Our first
result is an impossibility result:
  We show that no $(k,t)$-robust consensus protocol can solve consensus in the
crash model if $k+2t\geq n$ unless there is a particular punishment strategy,
called the $(k,t)$-baiting strategy. This reveals the need to introduce baiting
as the act of rewarding a colluding node when betraying its coalition, to make
blockchains more secure.
  Our second result is an equivalence relation between crash fault tolerant
games and Byzantine fault tolerant games, which raises an interesting research
question on the power of baiting to solve consensus. To this end, we show, on
the one hand, that a $(k,t)$-robust consensus protocol becomes $(k+t,t)$-robust
in the crash model. We show, on the other hand, that the existence of a
$(k,t)$-robust consensus protocol in the crash model that does not make use of
a baiting strategy implies the existence of a $(k-t,t)$-robust consensus
protocol in the Byzantine model, with the help of cryptography.
