Why is Kasparov still alive?

One loyal MR reader wrote in the comments:

He’ll [Kasparov] be fine. Killing him would be too bad a move in terms of PR.

But that is exactly my worry.  Putin has many would-be enemies.  What better retaliation than to do something evil and make it look like Putin is possibly at fault?  (That is in fact one theory about the polonium poisonings.)  Maybe you think Putin has already signaled credibly that he wouldn’t kill Kasparov, but if that is the case then he could in fact turn around and order it done and not take the blame.  Either way the equilibrium looks like assassination.  The going rate for an assassin simply isn’t that high and surely somebody has at least that much at stake in the outcome.

When I was a little kid I saw TV coverage of the assassinations of Bobby Kennedy and Martin Luther King.  I recall wondering why every famous politician, or at least every reachable famous politician, isn’t assassinated.  Or why isn’t the equilibrium quantity of product sabotage — accompanied by options trading of course — very high?  The sabotage doesn’t have to hurt people to lower share prices.

If some people find it worthwhile to send spam, why don’t many more?  Is the cost structure really that heterogenous on the production side? 

I might add these are important questions for understanding a future of extreme nuclear proliferation.