Life insurance, in the past, was frequently illegal.
I'd argue that it should be illegal again, as a moral hazard (directly contributing to countless murders and other schemes) and as a particularly morbid form of gambling.
In the US, a reasonable estimate is dozens of murders per year. I don't know if we can do any better without running a study: There's no good data easily available; the murder clearance rate in the US is now quite low; most insurance killings are, of course, staged to look like accidents.
I'd argue that it should be illegal again, as a moral hazard (directly contributing to countless murders and other schemes) and as a particularly morbid form of gambling.